3 - Python Strings

Strings are sequence of Characters

In Python, specifically, strings are a sequence of Unicode Characters

* Creating Strings

* Accessing Strings

* Adding Chars to Strings

* Editing Strings

* Deleting Strings

* Operations on Strings

* String Functions

Creating Strings

Example 1

Explanation

• The code assigns the string value 'hello' to the variable s using different syntaxes including single quotes, double quotes, and triple quotes for both single and multi-line strings.
• It also demonstrates the use of the str() function to convert an object to a string, though in this case, it's redundant since 'hello' is already a string.
• The print() function is used to output the value of s to the console.
• Expected output is the string hello printed on the console.
• The use of triple quotes allows for multiline strings, although in this example, they contain only a single line.

Output

Example 2

Explanation

• The code assigns a string value to the variable s, which includes an apostrophe.
• It uses double quotes around the string to avoid syntax errors caused by the apostrophe.
• The print() function is called to display the value of s on the console.
• The expected output is the string it's raining outside.
• There are no side effects other than printing the string to the console.

Output

Accessing Substrings from a String

Example 3

Explanation

• The code accesses a character in the string s using positive indexing.
• s[6] retrieves the character at index 6 of the string s.
• The string s is 'hello world', where indexing starts from 0.
• The character at index 6 is a space (' ').
• The print function outputs the space character to the console.

Output

Example 4

Explanation

• The code accesses the last character of the string s using negative indexing.
• It uses the print() function to display the accessed character.
• The expected output is d, which is the last character of the string 'hello world'.
• Negative indexing in Python allows access to elements from the end of a sequence, where -1 refers to the last element.
• This code demonstrates how to use negative indices to retrieve specific characters from a string.

Output

Example 5

Explanation

• The code slices the string s from index 2 to 4 (not including index 5).
• It uses Python's string slicing feature.
• The expected output is llo, which is the substring of s starting at index 2 and ending at index 4.
• This operation does not modify the original string s; it simply extracts a portion of it.
• The print function is used to display the sliced substring.

Output

Example 6

Explanation

• The code slices the string s starting from index 2 to the end.
• It uses Python's string slicing feature where s[start:] returns a substring from the start index to the end of the string.
• The expected output is 'llo world', which is the part of the string s after the first two characters.
• This operation does not modify the original string s; it simply creates and prints a new substring.
• No side effects occur as the code only performs a read operation on the string.

Output

Example 7

Explanation

• The code slices the string s which contains the value 'hello world'.
• It uses Python's slicing syntax s[start:stop:step] where start is 0, stop is 6, and step is 2.
• This means it starts at the first character (index 0), goes up to but does not include the 7th character (index 6), and selects every second character in between.
• The expected output is 'hlo', as it takes characters at indices 0, 2, and 4 from the string 'hello world'.

Output

Example 8

Explanation

• The code slices the string s to exclude the last two characters.
• It uses Python's slicing feature where s[:-2] means "take the string s from the beginning up to, but not including, the second-to-last character."
• The key function here is the slicing operation itself, which is part of Python's string handling capabilities.
• The expected output is 'hello wor', as it prints the string s without the last two characters ('ld').

Output

Example 9

Explanation

• The code slices the string s from index 6 to index 0, moving backwards by 1 step each time.
• It uses Python's string slicing feature, where s[start:stop:step] is the syntax.
• The start index is 6, stop index is 0, and step is -1, indicating reverse slicing.
• The expected output is 'dlrow', which is the substring of s from 'w' to 'd' in reverse order.
• No side effects; it only prints the sliced string to the console.

Output

Example 10

Explanation

• The code reverses the string stored in the variable s.
• It uses Python's slicing feature where [::-1] indicates that the string should be traversed from the end to the beginning.
• The print() function is used to display the reversed string on the console.
• Expected output is the reversed version of the string s.
• There are no side-effects; it only outputs the reversed string.

Output

Example 11

Explanation

• Prints the last five characters of the string stored in variable s
• Uses Python's slicing feature to extract a substring
• The slice -5: indicates starting from the fifth character from the end to the end of the string
• Expected output is the last five characters of the string s
• If s has fewer than five characters, it prints the entire string s

Output

Example 12

Explanation

• The code prints a substring of the variable s in reverse order.
• It uses Python's slicing feature with the syntax s[start:stop:step].
• The start index is -1, which refers to the last character of the string s.
• The stop index is -6, indicating the position before the sixth character from the end, but since the step is negative, it includes up to the sixth character from the end.
• The step is -1, which means the slicing goes backwards through the string.
• Expected output is the last five characters of the string s in reverse order.

Output

Editing and Deleting in String

Example 13

Explanation

• The code attempts to change the first character of the string s from 'h' to 'H'.
• It uses indexing s[0] to access the first character of the string.
• The assignment s[0] = 'H' is intended to modify the string, but it will raise a TypeError because strings in Python are immutable.
• The print(s) statement is meant to display the modified string, but due to the error, it will not execute as intended.
• The comment # Python strings are immutable explains that strings cannot be changed after they are created, which is why the assignment operation fails.

Output

Example 14

Explanation

• The code attempts to delete the string variable s which is initially set to 'hello world'.
• It uses the del statement to remove the variable s from the current namespace.
• After deletion, attempting to print s will result in a NameError because s no longer exists.
• The expected side-effect is that the variable s is removed from memory.
• The expected output is an error message indicating that the name s is not defined.

Output

Example 15

Explanation

• The code attempts to delete characters from the string s using slicing.
• del s[-1:-5] is intended to remove characters from index -1 to -5, but since the start index is greater than the end index, it does nothing.
• The print(s) function outputs the original string s without any modifications.
• Expected output is hello world as the deletion operation has no effect on the string.
• This demonstrates how Python handles slicing with reversed indices in a deletion context.

Output

Operators on Strings

* Arithmetic Operators

* Relational Operators

* Logical Operators

* Loops on Strings

* Membership Operators

Example 16

Explanation

• The code concatenates two strings, 'Madhu' and 'Dadi', with a space in between.
• It uses the + operator to concatenate strings.
• The print() function is used to output the concatenated string to the console.
• Expected output is the string "Madhu Dadi".
• There are no side effects other than displaying the output on the console.

Output

Example 17

Explanation

• The code multiplies the string 'Madhu' by 5.
• It uses the * operator to repeat the string.
• The expected output is the string 'MadhuMadhuMadhuMadhuMadhu'.
• This operation does not have any side effects; it simply prints the result to the console.

Output

Example 18

Explanation

• Prints a string of asterisks (*) repeated 50 times.
• Uses the print() function to output the string to the console.
• The * operator is used to repeat the string.
• Expected output is a line of 50 asterisks.
• No side-effects other than displaying text on the console.

Output

Example 19

Explanation

• The code compares two strings, 'Delhi' and 'Mumbai', using the equality operator ==.
• It checks if the string 'Delhi' is exactly the same as the string 'Mumbai'.
• The comparison is case-sensitive, meaning 'Delhi' and 'delhi' would be considered different.
• The expected output of this comparison is False since 'Delhi' is not equal to 'Mumbai'.
• This operation does not have any side-effects; it simply returns a boolean value indicating the result of the comparison.

Output

Example 20

Explanation

• Compares the string 'Delhi' with the string 'delhi' for inequality.
• Uses the != operator to check if the two strings are not equal.
• The comparison is case-sensitive, meaning 'Delhi' and 'delhi' are considered different.
• Returns True because the strings differ in case.
• No side-effects; simply evaluates and returns a boolean value.

Output

Example 21

Explanation

• Compares the string 'Mumbai' with the string 'Pune' lexicographically.
• Uses the greater than (>) operator to perform the comparison based on ASCII values of characters.
• Returns False because 'Mumbai' comes before 'Pune' in lexicographical order.
• Demonstrates how Python compares strings character by character from left to right.
• No side effects; simply evaluates the expression and returns a boolean value.

Output

Example 22

Explanation

• Compares the string 'Pune' with the string 'Mumbai' lexicographically.
• Uses the greater than (>) operator to determine if 'Pune' comes after 'Mumbai' in dictionary order.
• Returns True because 'Pune' is lexicographically greater than 'Mumbai'.
• No side effects; simply evaluates the comparison and returns a boolean value.
• Expected output is True.

Output

Example 23

Explanation

• The code compares two strings: 'Pune' and 'pune'.
• It uses the greater than (>) operator to compare the ASCII values of the characters in the strings.
• The comparison is case-sensitive, meaning uppercase letters have lower ASCII values than lowercase letters.
• The expected output is False because the ASCII value of 'P' (80) is less than the ASCII value of 'p' (112).
• This comparison reflects the lexicographical order based on ASCII values, where 'Pune' comes before 'pune'.

Output

Example 24

Explanation

• The code performs a logical AND operation between two string literals, 'hello' and 'world'.
• In Python, non-empty strings are considered True in a boolean context.
• The and operator returns the second operand if both operands are truthy; otherwise, it returns the first operand that is falsy.
• Since both 'hello' and 'world' are truthy, the expression evaluates to 'world'.
• This cell does not have any side effects; it simply evaluates the expression and returns the result.

Output

Example 25

Explanation

• The code evaluates an expression using the logical or operator between two string literals.
• In Python, the or operator returns the first truthy value it encounters or the last value if none are truthy.
• Both 'hello' and 'world' are non-empty strings, which are considered truthy in Python.
• Therefore, the expression evaluates to 'hello', as it is the first truthy value.
• This code does not have any side effects; it simply returns a value.

Output

Example 26

Explanation

• The code evaluates an expression that uses the logical AND operator (and) between two string literals.
• The first string is an empty string (''), which is considered False in a boolean context.
• The second string is 'world', which is considered True in a boolean context.
• Since the first operand is False, the expression short-circuits and returns the first operand without evaluating the second.
• The expected output of this expression is an empty string ('').

Output

Example 27

Explanation

• The code evaluates an expression using the or operator between two string literals.
• The or operator returns the first truthy value it encounters. In Python, non-empty strings are considered truthy.
• Since 'world' is not an empty string, it is evaluated as truthy.
• The expression will return 'world' because it is the first truthy value in the evaluation.
• There are no side effects; the code simply returns a value.

Output

Example 28

Explanation

• The code evaluates the logical NOT of the string 'hello'
• In Python, non-empty strings are considered True in a boolean context
• The not operator negates the boolean value, so it returns False
• There are no key functions or APIs used in this simple expression
• The expected output is False

Output

Example 29

Explanation

• Evaluates whether the empty string is considered False in a boolean context
• Uses the not operator to invert the truth value of the empty string
• The empty string '' is inherently False in Python
• The result of not '' is True
• No side effects; simply returns a boolean value

Output

Example 30

Explanation

• Iterates over each character in the string 'hello'
• Uses the for loop to go through each element in the iterable (string in this case)
• The variable i takes on the value of each character in the string during each iteration
• Calls the print() function to output each character on a new line
• Expected output is each letter of 'hello' printed individually: h e l l o

Output

Example 31

Explanation

• The code iterates over each character in the string 'delhi'.
• For each character in the string, it prints the word 'pune'.
• Key function used is print(), which outputs text to the console.
• Expected output is the word 'pune' printed five times, once for each character in 'delhi'.
• There are no side effects other than the console output.

Output

Example 32

Explanation

• The code checks if the character 'd' is present in the string 'delhi'.
• It uses the in operator, which is a membership operator in Python.
• The expected output is True, as 'd' is indeed a member of the string 'delhi'.

Output

Example 33

Explanation

• The code checks if the character 'd' is not present in the string 'Delhi'.
• It uses the not in operator to perform the membership test.
• The expected output is a boolean value, True, because 'd' (lowercase) is not found in 'Delhi' (which contains 'D' uppercase).
• This operation is case-sensitive, meaning it distinguishes between uppercase and lowercase letters.
• There are no side-effects; the code simply evaluates and returns a boolean result.

Output

Common Functions

* len

* max

* min

* sorted

Example 34

Explanation

• The code calculates the length of the string 'hello world'.
• It uses the built-in len() function to determine the number of characters in the string.
• The expected output is an integer representing the total number of characters, which is 11 in this case.
• This code does not have any side effects; it simply returns the length of the string.
• The space between 'hello' and 'world' is counted as one character in the length calculation.

Output

Example 35

Explanation

• The code finds the maximum character in the string 'hello world' based on ASCII values.
• It uses the built-in max() function to determine the highest ASCII value among the characters in the string.
• The expected output is the character 'w', which has the highest ASCII value in the given string.
• This operation does not have any side effects; it simply returns the result of the comparison.
• The function compares each character's ASCII value, where 'w' (ASCII 119) is greater than all other characters in the string.

Output

Example 36

Explanation

• The code finds the minimum character in the string 'hello world' based on ASCII values.
• It uses the built-in min() function which returns the smallest item in an iterable.
• The expected output is the character ' ' (space), as it has the lowest ASCII value among all characters in the string.
• This operation does not have any side effects; it simply returns a value.
• The comparison is case-sensitive, meaning uppercase letters would be considered smaller than lowercase letters if present.

Output

Example 37

Explanation

• The code sorts the characters in the string 'hello world'.
• Uses the built-in sorted() function which returns a new list containing all items from the iterable in ascending order.
• Sorting is based on ASCII values, so spaces come before letters.
• Expected output is a list of characters: [' ', 'd', 'e', 'h', 'l', 'l', 'l', 'o', 'o', 'r', 'w'].
• No side-effects; the original string remains unchanged.

Output

Capitalize / Title / Upper / Lower / Swapcase

Example 38

Explanation

• The code assigns the string 'hello world' to the variable s.
• It then calls the capitalize() method on the string s.
• The capitalize() method converts the first character of the string to uppercase and the rest to lowercase.
• This operation does not modify the original string s but returns a new capitalized string.
• The expected output is 'Hello world', which is not stored or printed in this code snippet.

Output

Example 39

Explanation

• Converts the string s to title case, capitalizing the first letter of each word.
• Uses the title() method, which is a built-in string method in Python.
• Expected output is a new string where the first character of each word is uppercase and the rest are lowercase.
• Does not modify the original string s; instead, it returns a new string with the title case transformation.
• Side-effect is none, as strings in Python are immutable and the method does not alter the input string directly.

Output

Example 40

Explanation

• Converts all lowercase letters in the string s to uppercase.
• Uses the upper() method, which is a built-in string method in Python.
• Does not modify the original string s; instead, it returns a new string with all characters in uppercase.
• Expected output is a string where all alphabetic characters are converted to their uppercase equivalents.
• If s contains no lowercase letters, the returned string will be identical to s.

Output

Example 41

Explanation

• Converts all uppercase characters in the string s to lowercase.
• Uses the lower() method, which is a built-in string method in Python.
• Does not modify the original string s; instead, it returns a new string with all characters in lowercase.
• Expected output is a string where all alphabetic characters are in lowercase.
• No side-effects; the original string remains unchanged.

Output

Example 42

Explanation

• Converts all uppercase letters to lowercase and vice versa in the string 'HeLlO WorLD'
• Uses the swapcase() method which is a built-in string function in Python
• Expected output is the string 'hElLo wORld'
• No side-effects as strings in Python are immutable and the method returns a new string
• Demonstrates string manipulation and case conversion in Python

Output

Count / Find / Index

Example 43

Explanation

• The code counts the number of times the character 'i' appears in the string 'my name is madhu'.
• It uses the count() method, which is a built-in string method in Python.
• The expected output is an integer representing the count of 'i' in the string.
• In this case, the output will be 1 because 'i' appears once in the string.
• There are no side-effects; the method simply returns a value without modifying the original string.

Output

Example 44

Explanation

• The code counts the number of times the character 'm' appears in the string 'my name is madhu'.
• It uses the count() method, which is a built-in string method in Python.
• The expected output is an integer representing the count of 'm', which is 2 in this case.
• This method is case-sensitive, so it only counts lowercase 'm'.
• There are no side-effects; it simply returns the count without modifying the original string.

Output

Example 45

Explanation

• The code searches for the substring 'madhu' within the string 'my name is madhu'.
• It uses the find() method, which returns the lowest index of the substring if it is found.
• If the substring is not found, the find() method would return -1.
• In this case, since 'madhu' is present, the expected output is the index 7, where 'madhu' starts in the string.
• This operation does not modify the original string; it simply returns an integer value indicating the position.

Output

Example 46

Explanation

• The code searches for the substring 'is' within the string 'my name is madhu'.
• It uses the find method, which returns the lowest index of the substring if it is found.
• If the substring is not found, the find method would return -1, but in this case, 'is' is present.
• The expected output is 5, as 'is' starts at the 5th index of the string (considering 0-based indexing).
• This operation does not have any side effects; it simply returns an integer value.

Output

Example 47

Explanation

• The code searches for the substring 'x' within the string 'my name is madhu'.
• It uses the find() method, which returns the lowest index of the substring if it is found.
• If the substring is not found, as in this case, find() returns -1.
• The expected output is -1 since 'x' does not exist in the string 'my name is madhu'.
• There are no side effects; the method simply returns an integer value.

Output

Example 48

Explanation

• The code finds the starting index of the substring 'is' within the string 'my name is madhu'.
• It uses the index() method, which searches for the first occurrence of the specified value and returns its position.
• The expected output is the integer 7, as 'is' starts at the 7th index of the string (considering the first character is at index 0).
• If the substring is not found, the index() method would raise a ValueError.
• This operation does not modify the original string; it simply returns the index position.

Output

Example 49

Explanation

• The code attempts to find the index of the substring 'x' within the string 'my name is madhu'.
• It uses the index() method, which searches for the first occurrence of the specified value and returns its position.
• If the substring is not found, the index() method raises a ValueError.
• In this case, since 'x' is not present in the string, a ValueError will be raised.
• The comment indicates that the difference between find() and index() is that find() returns -1 if the substring is not found, whereas index() raises an error.

Output

endswith / startswith

Example 50

Explanation

• The code checks if the string 'my name is madhu' ends with the substring 'madhu'.
• It uses the endswith() method, which is a string method in Python.
• The method returns True if the string ends with the specified suffix, otherwise it returns False.
• In this case, the expected output is True because the string does indeed end with 'madhu'.
• There are no side-effects; the method simply returns a boolean value.

Output

Example 51

Explanation

• The code checks if the string 'my name is madhu' ends with the substring 'aa'.
• It uses the endswith() method, which is a built-in string method in Python.
• The method returns a boolean value: True if the string ends with the specified suffix, otherwise False.
• In this case, the expected output is False because the string does not end with 'aa'.
• This operation does not have any side effects; it simply evaluates and returns the result.

Output

Example 52

Explanation

• The code checks if the string 'my name is madhu' begins with the character 'm'.
• It uses the startswith() method, which is a string method in Python.
• The method returns a boolean value: True if the string starts with the specified prefix, otherwise False.
• In this case, the expected output is True because the string does indeed start with 'm'.
• There are no side effects; the method simply evaluates and returns a boolean.

Output

Example 53

Explanation

• The code checks if the string 'my name is madhu' starts with the substring 'madhu'.
• It uses the startswith() method, which is a string method in Python.
• The method returns False because the string does not start with 'madhu'; it starts with 'my'.
• No side effects; it simply evaluates and returns a boolean value.
• Expected output is False.

Output

Format

Example 54

Explanation

• The code creates two variables, name and gender, with the values 'madhu' and 'male', respectively.
• It uses the format() method of string objects to insert the values of name and gender into the placeholders {} within the string.
• The format() method replaces the first placeholder {} with the value of name and the second placeholder {} with the value of gender.
• The expected output is the string 'Hi my name is madhu and I am a male'.

Output

Example 55

Explanation

• The code creates two string variables, name and gender, with values 'madhu' and 'male' respectively.
• It uses the format() method of strings to insert the values of gender and name into a template string.
• The placeholders {1} and {0} in the template string refer to the second and first arguments passed to the format() method, respectively.
• The expected output of this code is the string 'Hi my name is madhu and I am a male'.
• This code does not have any side effects; it simply returns a formatted string.

Output

isalnum / isalpha / isdigit / isidentifier

Example 56

Explanation

• The code checks if the string 'madhu245' consists only of alphanumeric characters (letters and numbers).
• It uses the isalnum() method, which is a built-in string method in Python.
• The method returns True if all characters in the string are alphanumeric and there is at least one character, otherwise it returns False.
• In this case, since 'madhu245' contains only letters and numbers, the expected output is True.
• The comment # Alphanumeric indicates that the string being checked is expected to be alphanumeric.

Output

Example 57

Explanation

• The code checks if the string 'madhu245%' consists only of alphanumeric characters.
• It uses the isalnum() method, which returns True if all characters in the string are alphanumeric and there is at least one character, otherwise it returns False.
• The string contains non-alphanumeric characters ('%'), so the expected output is False.

Output

Example 58

Explanation

• Checks if all characters in the string 'madhu245' are alphabetic.
• Uses the isalpha() method, which returns True if all characters in the string are alphabetic and there is at least one character, otherwise it returns False.
• Expected output is False because the string contains numeric characters ('2', '4', '5').

Output

Example 59

Explanation

• The code checks if all characters in the string 'madhu' are alphabetic.
• It uses the isalpha() method, which returns True if all characters in the string are alphabetic and there is at least one character, otherwise it returns False.
• Expected output is True because the string 'madhu' contains only alphabetic characters.
• This method is useful for validating input where only letters are allowed.
• The comment # Alphabets only indicates the purpose of the check.

Output

Example 60

Explanation

• Checks if the string 'madhu245' consists solely of digit characters.
• Uses the isdigit() method, which returns True if all characters in the string are digits and there is at least one character, otherwise returns False.
• Expected output is False because the string contains non-digit characters ('m', 'a', 'd', 'h', 'u').
• No side-effects; it simply evaluates and returns a boolean value.

Output

Example 61

Explanation

• The code checks if the string '123' consists solely of digit characters.
• It uses the isdigit() method, which is a built-in string method in Python.
• The method returns True if all characters in the string are digits and there is at least one character, otherwise it returns False.
• In this case, since '123' contains only digits, the expected output is True.
• There are no side effects; the method simply evaluates and returns a boolean value.

Output

Example 62

Explanation

• Checks if the string '1name' is a valid Python identifier.
• Uses the isidentifier() method of the string class.
• Returns False because identifiers cannot start with a digit in Python.
• Expected output is a boolean value indicating the validity of the string as an identifier.
• No side effects; simply evaluates and returns the result.

Output

Example 63

Explanation

• Checks if the string 'name1' is a valid Python identifier.
• Uses the isidentifier() method which returns True if the string is a valid identifier according to Python's language definition.
• A valid identifier must start with a letter or underscore, followed by any number of letters, digits, or underscores.
• Expected output is True since 'name1' starts with a letter and contains only letters and digits.
• No side effects, simply returns a boolean value.

Output

Example 64

Explanation

• Checks if the string 'first_name' is a valid Python identifier
• Uses the isidentifier() method of string objects
• Returns True if 'first_name' is a valid identifier, otherwise False
• In this case, it will return True because 'first_name' follows Python's rules for identifiers (starts with a letter or underscore, followed by any number of letters, digits, or underscores)

Output

Example 65

Explanation

• Checks if the string 'first-name' is a valid Python identifier.
• Uses the isidentifier() method of string objects.
• Returns False because hyphens are not allowed in Python identifiers.
• Expected output is a boolean value indicating validity as an identifier.
• No side-effects; simply evaluates and returns a result.

Output

Split / Join

Example 66

Explanation

• The code splits the string 'hi my name is madhu' into a list of words.
• It uses the split() method, which by default splits the string at any whitespace.
• The expected output is a list containing the words ['hi', 'my', 'name', 'is', 'madhu'].
• There are no side effects; it simply returns a new list without modifying the original string.

Output

Example 67

Explanation

• The code splits the string 'hi my name is madhu' into a list of substrings.
• It uses the split() method, which divides the string at each occurrence of the specified separator, 'i' in this case.
• The expected output is a list containing the substrings ['h', ' my name s m', 'du'].
• This operation does not modify the original string but returns a new list.
• The split() method is useful for breaking down strings into components based on a delimiter.

Output

Example 68

Explanation

• Joins a list of strings into a single string with spaces between each element
• Uses the join() method of a string object, which concatenates the elements of an iterable (in this case, a list) into a single string
• The iterable contains the words 'hi', 'my', 'name', 'is', 'madhu'
• Expected output is the string "hi my name is madhu"
• No side-effects; simply returns the concatenated string

Output

Example 69

Explanation

• The code concatenates a list of strings into a single string.
• It uses the join() method of a string object, which takes an iterable (in this case, a list) and joins its elements separated by the string on which join() is called.
• The string '-' is used as a separator between each element of the list.
• The expected output is the string 'hi-my-name-is-madhu'.
• There are no side effects; the function returns a new string and does not modify the original list.

Output

Replace

Example 70

Explanation

• The code replaces the substring 'madhu' with 'dadi' in the string 'hi my name is madhu'.
• Key function used is replace(), which is a string method in Python.
• Expected output is the string 'hi my name is dadi'.
• There are no side-effects as strings in Python are immutable, meaning the original string remains unchanged.
• The replace() function returns a new string with the specified replacements.

Output

Example 71

Explanation

• The code attempts to replace occurrences of the substring 'aaaa' with 'dadi' in the string 'hi my name is madhu'.
• The replace function is used here, which is a string method in Python.
• Since 'aaaa' does not exist in the original string, the string remains unchanged.
• The expected output of this code is 'hi my name is madhu'.
• There are no side-effects; the operation does not modify any external variables or state.

Output

Strip

Example 72

Explanation

• The code removes any leading and trailing whitespace characters from the string 'Madhu '.
• It uses the strip() method, which is a built-in string function in Python.
• The expected output is the string 'Madhu' without any trailing spaces.
• There are no side-effects; the original string remains unchanged as strings are immutable in Python.
• The result of this operation would typically be assigned to a variable or used directly in further operations.

Output

Example 73

Explanation

• The code removes leading and trailing hyphens from the string 'Madhu----------'.
• It uses the strip() method of Python strings, which is designed to remove specified characters from the beginning and end of a string.
• The argument '-' passed to strip() indicates that hyphens should be removed.
• The expected output is the string 'Madhu' without any leading or trailing hyphens.
• There are no side-effects; the operation returns a new string and does not modify the original string.

Output

Example Programs

Example 74

Explanation

• The code prompts the user to enter a string.
• It initializes a variable counter to zero, which will be used to count the number of characters in the string.
• A for loop iterates over each character in the string s, incrementing the counter by one for each character.
• After the loop completes, the code prints the total count of characters in the string, which represents the length of the string.
• The expected output is a message displaying the length of the string entered by the user.

Output

Example 75

Explanation

• The code prompts the user to enter an email address.
• It uses the find method to locate the position of the '@' symbol in the email string.
• The code then slices the string from the beginning up to (but not including) the '@' symbol's position.
• This sliced string, which represents the username part of the email, is printed to the console.
• If the '@' symbol is not found, the find method returns -1, and the entire input string is printed as the username.

Output

Example 76

Explanation

• Prompts the user to enter a string and stores it in the variable s
• Asks the user for a specific character to search for within the string and stores it in the variable term
• Initializes a counter variable to zero, which will keep track of how many times term appears in s
• Iterates through each character in the string s, checking if it matches term; if it does, increments the counter by one
• Outputs the total frequency of the character term found in the string s

Output

Example 77

Explanation

• Prompts the user to enter a string and stores it in the variable s
• Asks the user for a specific term to search within the string and stores it in the variable term
• Uses the count method of the string object s to find how many times term appears in s
• Prints out the frequency of the term in the format "frequency is X", where X is the count
• Expects the user to input a string and a term, and outputs the number of occurrences of the term in the string

Output

Example 78

Explanation

• The code prompts the user to enter a string and a character they wish to remove from that string.
• It initializes an empty string result to accumulate characters that are not the one to be removed.
• The code iterates over each character i in the input string s.
• If the current character i is not equal to the character specified in term, it appends i to result.
• Finally, the code prints the modified string result which has all instances of the specified character removed.

Output

Example 79

Explanation

• The code prompts the user to enter a string.
• It checks if the string is equal to its reverse (s[::-1]).
• If the string is the same forwards and backwards, it prints 'Palendrome'.
• If the string is not the same forwards and backwards, it prints 'Not Palendrome'.
• The expected output is either 'Palendrome' or 'Not Palendrome', depending on the user's input.

Output

Example 80

Explanation

• The program checks if the input string is a palindrome by comparing characters from the beginning and end moving towards the center.
• input('Enter a string:') is used to take a string input from the user.
• The for loop iterates over the first half of the string, comparing each character with its corresponding character from the end.
• If any pair of characters doesn't match, flag is set to False and the loop breaks, indicating the string is not a palindrome.
• Depending on the value of flag, the program prints 'Palendrome' if all characters matched correctly, otherwise it prints 'Not Palendrome'. Note: There is a typo in the word 'Palindrome'.

Output

Example 81

Explanation

• The code prompts the user to enter a string.
• It initializes an empty list L to store words and a temporary string temp to build each word.
• It iterates over each character i in the input string s.
• If the character is not a space, it adds the character to temp; otherwise, it appends temp to the list L and resets temp to an empty string.
• After the loop, it appends the last temp to L to ensure the final word is included, then prints the list L containing all the words from the input string.

Output

Example 82

Explanation

• The code takes a string input from the user.
• It splits the string into words using the split() method.
• For each word, it capitalizes the first letter using upper() and makes the rest of the letters lowercase using lower(), then appends the modified word to list L.
• It prints the list L containing the words in title case.
• It joins the list L into a single string with spaces between words using join() and prints the resulting title-cased string.

Output

Example 83

Explanation

• The code converts an integer input by the user into its string representation.
• It uses the input() function to take user input and int() to convert it to an integer.
• The while loop continues until the number is reduced to zero, extracting each digit by using the modulus operator % and integer division //.
• Inside the loop, it prepends the corresponding character from the digits string to the result string based on the current least significant digit of number.
• Finally, it prints the result, which is the string representation of the original integer.

Output

Problem 1 - Print the following pattern. Write a program to use for loop to print the following reverse number pattern.

Example 84

Explanation

• Prompts the user to enter the number of rows for a pattern.
• Uses nested loops to print numbers in descending order for each row.
• The outer loop iterates over the range from 0 to the number of rows specified by the user.
• The inner loop counts down from the current row number to 1, printing each number followed by a space.
• Prints a new line after completing each row's number sequence, resulting in a right-angled triangle pattern of numbers.

Output

Problem 2: Print the following pattern.

Example 85

Explanation

• The code prompts the user to enter the number of rows for a pattern.
• It uses nested for loops to print a pyramid pattern of asterisks (*) based on the input number of rows.
• The first loop constructs the upper half of the pyramid by printing increasing numbers of asterisks on each line.
• The second loop constructs the lower half of the pyramid by printing decreasing numbers of asterisks on each line.
• The print('*', end=' ') statement prints an asterisk followed by a space without moving to a new line, allowing multiple asterisks to be printed on the same line.
• The print() statement after the inner loops moves the cursor to the next line after printing each row of asterisks.

Output

Problem 3:Write a program to pring the following pattern

---

---

Example 86

Explanation

• The code prints a right-aligned pattern of asterisks (*) forming a triangle.
• It uses the range function to iterate from 1 to rows (inclusive), where rows is initially set to 6.
• The print function is used twice in each iteration: first to print spaces for alignment, and second to print the asterisks.
• The end='' parameter in the first print call prevents moving to a new line after printing spaces.
• In each iteration, the number of spaces decreases by 1 and the number of asterisks increases by 1, creating a right-aligned triangular pattern of asterisks.

Output

Problem 4:Write a program to print the following pattern

1

2 1

3 2 1

4 3 2 1

5 4 3 2 1

Example 87

Explanation

• The code prints a pattern of numbers in descending order for each row, starting from 1 up to the specified number of rows.
• It uses the range() function to generate sequences of numbers for both the outer and inner loops.
• The outer loop iterates over the range from 1 to rows + 1, controlling the number of rows.
• The inner loop iterates backward from the current row number i down to 1, printing each number followed by a space on the same line.
• Each row ends with a newline character, resulting in a pyramid-like pattern of numbers printed to the console.

Output

Problem 5: Write a Python Program to Find the Sum of the Series till the nth term:

1 + x^2/2 + x^3/3 + … x^n/n n will be provided by the user

Example 88

Explanation

• Initializes variables x and n with values 10 and 5 respectively.
• Uses a loop to calculate the sum of the series 1 + x^2/2 + x^3/3 + ... + x^n/n.
• Constructs a string s that represents the series in a readable format.
• Prints the series without the trailing '+' symbol.
• Outputs the calculated sum of the series.

Output

Problem 6: The natural logarithm can be approximated by the following series.

If x is input through the keyboard, write a program to calculate the sum of the first seven terms of this series.

Example 89

Explanation

• The code calculates a partial sum of a series where each term is (1/i) * ((x-1)/x)^i for i ranging from 1 to n.
• It uses the range() function to iterate from 1 to n inclusive.
• The format() method is used to construct a string s that represents the series in a readable format.
• The final string s has a trailing + which is removed before printing using s[:-1].
• The code prints the constructed series string without the last + and the calculated sum of the series.

Output

Problem 7 - Find the sum of the series upto n terms.

Write a program to calculate the sum of series up to n term. For example, if n =5 the series will become 2 + 22 + 222 + 2222 + 22222 = 24690. Take the user input and then calculate. And the output style should match which is given in the example.

Example 1:

Input:

Output:

Example 90

Explanation

• Prompts the user to enter the number of terms they want in the sequence.
• Initializes start to 2 and sum to 0 to begin the sequence and keep track of the total sum.
• Iterates n times, printing each term of the sequence followed by a '+' except for the last term.
• In each iteration, adds the current start value to sum.
• Updates start to the next term in the sequence by multiplying it by 10 and adding 2.
• After the loop, prints the final sum of the sequence.

Output

###Problem 8: Write a program to print all the unique combinations of 1,2,3 and 4

Output:

Example 91

Explanation

• The code uses nested loops to iterate over four ranges, each from 1 to 4.
• It prints out all possible combinations of four numbers, where each number is between 1 and 4 inclusive.
• The range(1,5) function generates numbers starting from 1 up to, but not including, 5.
• The print(i,j,k,m) statement outputs the current values of i, j, k, and m on each iteration.
• The expected output is a list of 256 tuples, each representing a unique combination of four numbers from 1 to 4.

Output

###Problem 9: Write a program that will take a decimal number as input and prints out the binary equivalent of the number

Example 92

Explanation

• Prompts the user to enter a number and converts it to an integer.
• Initializes an empty list named binary to store binary digits.
• Uses a while loop to repeatedly divide the number by 2, appending the remainder to the binary list until the number becomes 0.
• Prints the current value of n and the updated binary list after each division.
• Iterates over the binary list in reverse order, printing each element without a newline, to display the binary representation of the entered number.

Output

###Problem 10: Write a program that will take 2 numbers as input and prints the LCM and HCF of those 2 numbers

Example 93

Explanation

• The code prompts the user to enter two numbers.
• It calculates the Least Common Multiple (LCM) of the two numbers using a while loop that increments the greater of the two numbers until it finds a number divisible by both.
• It calculates the Highest Common Factor (HCF), also known as the Greatest Common Divisor (GCD), of the two numbers using a for loop that checks each number from 1 to the smaller of the two numbers to see if it divides both without a remainder.
• The LCM and HCF of the entered numbers are printed to the console.
• The code uses input() to get user input, int() to convert the input to integers, and basic arithmetic operations like modulus (%) to determine divisibility.

Output

Problem 11: Create Short Form from initial character

Given a string create short form ofthe string from Initial character. Short form should be capitalised.

Example:

Input:

Output:

Example 94

Explanation

• The code takes a string inp containing "Data science mentorship program".
• It initializes an empty string res to accumulate results.
• It splits the input string into words using split() method.
• For each word, it converts the first character to uppercase using i[0].upper() and appends it to res.
• Finally, it prints res, which will be "Dsmp" - the first letter of each word in uppercase.

Output

###Problem 12: Append second string in the middle of first string

Input:

Output:

Example 95

Explanation

• Prompts the user to enter two strings, storing them in variables s1 and s2.
• Calculates the midpoint of s1 using integer division of its length by 2.
• Concatenates the first half of s1, the entire s2, and the second half of s1.
• Prints the resulting concatenated string to the console.

Output

Problem 13:Given string contains a combination of the lower and upper case letters. Write a program to arrange the characters of a string so that all lowercase letters should come first.

Given:

str1 = PyNaTive

Expected Output:

yaivePNT

Example 96

Explanation

• The code iterates through each character in the string s.
• It checks if the character is lowercase using the islower() method.
• If the character is lowercase, it appends it to the lower string; otherwise, it appends it to the upper string.
• Finally, it prints the concatenation of lower and upper, which results in all lowercase letters of s followed by all uppercase letters.
• Expected output for the given string s is yaivePNt.

Output

Problem 14:Take a alphanumeric string input and print the sum and average of the digits that appear in the string, ignoring all other characters.

Input:

hel123O4every093

Output:

Example 97

Explanation

• The code iterates through each character in the string s.
• It checks if the character is a digit using the isdigit() method.
• If the character is a digit, it converts the character to an integer with int(i) and adds it to sum, while also incrementing count by 1.
• After the loop, it prints the total sum of all digits found in the string.
• It then prints the average of these digits by dividing sum by count.

Output

Problem 15: Removal of all characters from a string except integers

Given:

Expected Output:

Example 98

Explanation

• The code iterates over each character in the string s.
• It checks if the character is a digit using the isdigit() method.
• If the character is a digit, it appends it to the result string res.
• After the loop, res contains all the digits found in the original string concatenated together.
• The print(res) statement outputs the concatenated digits, which in this case would be 2510.

Output

Problem 16: Check whether the string is Symmetrical.

Statement: Given a string. the task is to check if the string is symmetrical or not. A string is said to be symmetrical if both the halves of the string are the same.

Example 1:

Input

Output

Example 99

Explanation

• The code prompts the user to enter a string.
• It checks if the length of the string is even or odd.
• If even, it splits the string into two halves; if odd, it splits the string into two halves excluding the middle character.
• It compares the two halves of the string.
• Prints 'Symmetric' if both halves are identical, otherwise prints 'Not Symmetric'.

Output

Problem 17: Reverse words in a given String

Statement: We are given a string and we need to reverse words of a given string.

Example 1:

Input:

Output:

Example 2:

Input:

Output:

Example 100

Explanation

• The code takes a string s containing "My name is Madhu Dadi".
• It splits the string into a list of words using the split() method, resulting in ['My', 'name', 'is', 'Madhu', 'Dadi'].
• Each word is appended to an initially empty list L.
• The list L is reversed using slicing [::-1], changing it to ['Dadi', 'Madhu', 'is', 'name', 'My'].
• The reversed list is joined back into a string with spaces between words using " ".join(L), and printed, resulting in "Dadi Madhu is name My".

Output

Problem 18: Find uncommon words from two Strings.

Statement: Given two sentences as strings A and B. The task is to return a list of all uncommon words. A word is uncommon if it appears exactly once in any one of the sentences, and does not appear in the other sentence. Note: A sentence is a string of space-separated words. Each word consists only of lowercase letters.

Example 1:

Input:

Output:

Example 101

Explanation

• The code initializes two strings, A and B, containing space-separated words.
• It creates an empty list L to store unique words that are not common between A and B.
• The first loop iterates over each word in string A. If a word is not found in string B and also not already in list L, it appends the word to L.
• The second loop iterates over each word in string B. Similarly, if a word is not found in string A and not in list L, it appends the word to L.
• Finally, the code prints the list L, which contains words unique to either or . Expected output for given and is .

Output

Problem 19: Word location in String.

Statement: Find a location of a word in a given sentence.

Example 1:

Input:

Output:

Note- Don't use index/find functions

Example 102

Explanation

• The code splits the string s into words and iterates over each word.
• It keeps track of the position of each word using the variable pos.
• If the current word matches the target word Madhu, the loop breaks.
• The final value of pos is printed, which represents the position of the word Madhu in the string s.
• Expected output is 6, as Madhu is the 6th word in the string.

Output

Problem 20: Write a program that can remove all the duplicate characters from a string. User will provide the input.

Example 103

Explanation

• The code iterates over each character in the string s.
• It checks if the character is not already present in the result string res.
• If the character is unique so far, it appends the character to res.
• After the loop, res contains all unique characters from s in the order they first appeared.
• The print(res) statement outputs the string 'abcdef', which consists of the unique characters from the original string.

Output