string manipulation

1

Concatenation: Combining two or more strings.

s1 = "Hello"
s2 = "World"
result = s1 + " " + s2  # Result: "Hello World"

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2

Repetition: Repeating a string multiple times.

s = "Hello"
result = s * 3  # Result: "HelloHelloHello"

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3

Slicing: Extracting a substring from a string.

s = "Hello World"
substring = s[0:5]  # Result: "Hello"

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4

Stripping: Removing leading and trailing whitespace.

s = "   Hello World   "
stripped = s.strip()  # Result: "Hello World"

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5

Splitting: Dividing a string into a list of substrings.

s = "Hello World"
parts = s.split()  # Result: ['Hello', 'World']

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6

Joining: Combining a list of strings into a single string.

words = ['Hello', 'World']
result = ' '.join(words)  # Result: "Hello World"

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7

Finding and Replacing: Locating substrings and replacing them.

s = "Hello World"
index = s.find("World")  # Result: 6 (starting index of "World")
new_s = s.replace("World", "Python")  # Result: "Hello Python"

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8

Upper and Lower Case: Converting to uppercase or lowercase.

s = "Hello World"
upper_s = s.upper()  # Result: "HELLO WORLD"
lower_s = s.lower()  # Result: "hello world"

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9

Formatting: Inserting values into a string template.

name = "Alice"
age = 30
formatted = f"My name is {name} and I am {age} years old."  # Result: "My name is Alice and I am 30 years old."

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10

Checking: Testing for specific properties.

s = "Hello"
is_alpha = s.isalpha()  # Result: True (all characters are alphabetic)
is_digit = s.isdigit()  # Result: False (not all characters are digits)

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11

Capitalizing: Capitalize the first letter of a string.

s = "hello world"
capitalized = s.capitalize()  # Result: "Hello world"

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12

Title Case: Capitalize the first letter of each word.

s = "hello world"
title_case = s.title()  # Result: "Hello World"

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13

Centering: Center-align a string within a specified width.

s = "hello"
centered = s.center(10, '-')  # Result: "--hello---"

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14

Justifying Left: Left-align a string within a specified width.

s = "hello"
left_justified = s.ljust(10, '-')  # Result: "hello-----"

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15

Justifying Right: Right-align a string within a specified width.

s = "hello"
right_justified = s.rjust(10, '-')  # Result: "-----hello"

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16

Removing Leading Whitespace: Remove whitespace from the beginning of a string.

s = "   hello"
lstrip_s = s.lstrip()  # Result: "hello"

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17

Removing Trailing Whitespace: Remove whitespace from the end of a string.

s = "hello   "
rstrip_s = s.rstrip()  # Result: "hello"

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18

Counting Substrings: Count occurrences of a substring.

s = "hello world world"
count = s.count("world")  # Result: 2

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19

Checking Start: Check if a string starts with a specific substring.

s = "hello world"
starts_with = s.startswith("hello")  # Result: True

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20

Checking End: Check if a string ends with a specific substring.

s = "hello world"
ends_with = s.endswith("world")  # Result: True

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21

Finding Substring: Find the index of the first occurrence of a substring.

s = "hello world"
index = s.find("world")  # Result: 6

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22

Finding Substring with a Start Position: Find the index of the first occurrence of a substring starting from a specified position.

s = "hello world world"
index = s.find("world", 7)  # Result: 12

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23

Finding Substring with a Start and End Position: Find the index of the first occurrence of a substring within a specified range.

s = "hello world world"
index = s.find("world", 0, 11)  # Result: 6

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24

Replacing with Count: Replace a substring with a new substring a specified number of times.

s = "hello world world"
replaced = s.replace("world", "Python", 1)  # Result: "hello Python world"

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25

Splitting with a Limit: Split a string into a list with a maximum number of splits.

s = "a,b,c,d"
parts = s.split(",", 2)  # Result: ['a', 'b', 'c,d']

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26

Joining with Separator: Join elements of a list into a single string with a specified separator.

parts = ['a', 'b', 'c']
result = '|'.join(parts)  # Result: "a|b|c"

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27

Finding All Substrings: Find all occurrences of a substring in a string.

import re
s = "hello world world"
matches = re.findall("world", s)  # Result: ['world', 'world']

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28

Splitting with Regular Expression: Split a string using a regular expression.

import re
s = "one1two2three3"
parts = re.split(r'\d+', s)  # Result: ['one', 'two', 'three', '']

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29

Substituting with Regular Expression: Replace occurrences of a pattern with a new string using a regular expression.

import re
s = "hello 123 world 456"
result = re.sub(r'\d+', '#', s)  # Result: "hello # world #"

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30

Escaping Special Characters: Escape special characters in a string.

import re
s = "hello. world?"
escaped = re.escape(s)  # Result: "hello\. world\?"

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31

Converting to Bytes: Convert a string to bytes.

s = "hello"
bytes_s = s.encode()  # Result: b'hello'

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32

Converting from Bytes: Convert bytes back to a string.

bytes_s = b'hello'
s = bytes_s.decode()  # Result: "hello"

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33

Encoding with a Specific Charset: Encode a string using a specific character set.

s = "hello"
encoded = s.encode('utf-16')  # Result: b'\xff\xfeh\x00e\x00l\x00l\x00o\x00'

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34

Decoding with a Specific Charset: Decode bytes using a specific character set.

encoded = b'\xff\xfeh\x00e\x00l\x00l\x00o\x00'
decoded = encoded.decode('utf-16')  # Result: "hello"

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35

Finding the Last Occurrence: Find the index of the last occurrence of a substring.

s = "hello world world"
index = s.rfind("world")  # Result: 12

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36

Finding the Last Occurrence with Start Position: Find the index of the last occurrence of a substring starting from a specified position.

s = "hello world world"
index = s.rfind("world", 0, 11)  # Result: 6

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37

Reversing a String: Reverse the characters in a string.

s = "hello"
reversed_s = s[::-1]  # Result: "olleh"

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38

Checking for Digits: Check if a string consists only of digits.

s = "12345"
is_digit = s.isdigit()  # Result: True

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39

Checking for Alphabetic Characters: Check if a string consists only of alphabetic characters.

s = "hello"
is_alpha = s.isalpha()  # Result: True

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40

Checking for Alphanumeric Characters: Check if a string consists only of alphanumeric characters.

s = "hello123"
is_alnum = s.isalnum()  # Result: True

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41

Checking for Numeric Characters: Check if a string is a numeric string (e.g., '123.45').

s = "123.45"
is_numeric = s.isnumeric()  # Result: False

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42

Checking for Lowercase: Check if all characters in a string are lowercase.

s = "hello"
is_lower = s.islower()  # Result: True

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43

Checking for Uppercase: Check if all characters in a string are uppercase.

s = "HELLO"
is_upper = s.isupper()  # Result: True

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44

Removing Substring: Remove all occurrences of a substring.

s = "hello world world"
result = s.replace("world", "")  # Result: "hello  "

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45

Padding with Characters: Pad a string with a specified character to reach a given length.

s = "hello"
padded = s.zfill(10)  # Result: "000000hello"

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46

Converting to String: Convert other data types to a string.

num = 123
s = str(num)  # Result: "123"

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47

Formatting Strings with f-strings: Format strings using f-strings (Python 3.6+).

name = "Alice"
age = 30
formatted = f"My name is {name} and I am {age} years old."  # Result: "My name is Alice and I am 30 years old."

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48

Using String Templates: Use the string.Template class for formatting.

from string import Template
t = Template("My name is $name and I am $age years old.")
result = t.substitute(name="Alice", age=30)  #Result: "My name is Alice and I am 30 years old." ```

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49

Formatting Strings with format(): Use the format() method for string formatting.

s = "My name is {} and I am {} years old."
formatted = s.format("Alice", 30)  # Result: "My name is Alice and I am 30 years old."

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50

Aligning Strings: Align strings in a given width with padding.

s = "hello"
aligned = "{:<10}".format(s)  # Left-align: "hello     "
aligned = "{:>10}".format(s)  # Right-align: "     hello"
aligned = "{:^10}".format(s)  # Center-align: "  hello   "

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51

Using String Escape Sequences: Include special characters in strings.

s = "Line 1\nLine 2\tTabbed"
# Result: "Line 1\nLine 2\tTabbed"

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52

Converting to Title Case: Convert each word's first letter to uppercase.

s = "hello world"
title_case = s.title()  # Result: "Hello World"

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53

Trimming Specific Characters: Trim specific characters from the beginning and end of a string.

s = "---hello---"
trimmed = s.strip('-')  # Result: "hello"

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54

Inserting Substrings: Insert a substring at a specific position.

s = "hello world"
result = s[:5] + " beautiful " + s[6:]  # Result: "hello beautiful world"

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55

Repeating Substrings: Repeat a substring a specific number of times.

s = "hello "
repeated = s * 3  # Result: "hello hello hello "

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56

Checking for Whitespace: Check if a string contains only whitespace.

s = "   "
is_space = s.isspace()  # Result: True

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57

Padding with a String: Pad a string with another string to a specific length.

s = "abc"
padded = s.ljust(10, '*')  # Result: "abc*******"

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58

Removing Trailing Characters: Remove trailing characters.

s = "hello!!!"
removed = s.rstrip('!')  # Result: "hello"

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59

Finding Substring with Regular Expression: Find substrings matching a pattern.

import re
s = "hello 123 world"
match = re.search(r'\d+', s)  # Result: <re.Match object; span=(6, 9), match='123'>

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60

Splitting Lines: Split a string into lines.

s = "line1\nline2\nline3"
lines = s.splitlines()  # Result: ['line1', 'line2', 'line3']

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61

Extracting Substrings with Regular Expressions: Use regex groups to extract parts of a string.

import re
s = "name: Alice, age: 30"
match = re.search(r'name: (\w+), age: (\d+)', s)
name, age = match.groups()  # Result: ('Alice', '30')

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62

Padding with Zeroes: Pad a string with zeroes to ensure a fixed length.

s = "42"
padded = s.zfill(5)  # Result: "00042"

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63

Splitting and Extracting by Separator: Split by a separator and extract specific parts.

s = "a,b,c,d"
parts = s.split(',')  # Result: ['a', 'b', 'c', 'd']
second = parts[1]  # Result: 'b'

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64

Replacing with Function: Use a function to replace substrings.

import re
def replace_func(match):
    return match.group(0).upper()
s = "hello world"
result = re.sub(r'\w+', replace_func, s)  # Result: "HELLO WORLD"

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65

Using String Interpolation: Format strings with interpolation (Python 2 style).

name = "Alice"
age = 30
formatted = "My name is %s and I am %d years old." % (name, age)  # Result: "My name is Alice and I am 30 years old."

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66

Using format_map() for Dictionary: Format strings using a dictionary.

data = {'name': 'Alice', 'age': 30}
template = "My name is {name} and I am {age} years old."
formatted = template.format_map(data)  # Result: "My name is Alice and I am 30 years old."

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67

Checking for Printable Characters: Check if all characters are printable.

s = "Hello, World!"
is_printable = s.isprintable()  # Result: True

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68

Finding Non-Printable Characters: Check if a string contains non-printable characters.

s = "Hello\x00World"
contains_non_printable = not s.isprintable()  # Result: True

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69

Finding Substring Using index(): Find the index of the first occurrence of a substring (raises an error if not found).

s = "hello world"
index = s.index("world")  # Result: 6

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70

Finding Last Occurrence Using rindex(): Find the index of the last occurrence of a substring (raises an error if not found).

s = "hello world world"
index = s.rindex("world")  # Result: 12

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71

Replacing Multiple Substrings: Replace multiple substrings using a loop or dictionary.

s = "hello world"
replacements = {"hello": "hi", "world": "everyone"}
for old, new in replacements.items():
    s = s.replace(old, new)  # Result: "hi everyone"

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72

Joining with Multiple Separators: Use multiple separators for joining elements.

parts = ['a', 'b', 'c']
result = ' - '.join(parts)  # Result: "a - b - c"

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73

Getting the ASCII Code: Get the ASCII code of a character.

s = "A"
ascii_code = ord(s)  # Result: 65

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74

Converting ASCII Code to Character: Convert an ASCII code to a character.

ascii_code = 65
character = chr(ascii_code)  # Result: 'A'

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75

Checking for Numeric String with Decimal: Check if a string represents a numeric value with a decimal point.

s = "123.45"
is_numeric = s.replace('.', '', 1).isdigit()  # Result: True

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76

Finding Substrings with Overlapping Matches: Find overlapping occurrences using regex.

import re
s = "aaaa"
matches = [m.start() for m in re.finditer(r'a', s)]  # Result: [0, 1, 2, 3]

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77

Using Named Groups in Regex: Extract named groups from a regex match.

import re
s = "name: Alice, age: 30"
match = re.search(r'name: (?P<name>\w+), age: (?P<age>\d+)', s)
name = match.group('name')  # Result: 'Alice'
age = match.group('age')  # Result: '30'

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78

Checking if String Contains Only Lowercase: Check if all characters are lowercase.

s = "hello"
is_lower = s.islower()  # Result: True

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79

Checking if String Contains Only Uppercase: Check if all characters are uppercase.

s = "HELLO"
is_upper = s.isupper()  # Result: True

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80

Converting String to List of Characters: Convert a string to a list of its characters.

s = "hello"
char_list = list(s)  # Result: ['h', 'e', 'l', 'l', 'o']

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81

Converting List of Characters to String: Convert a list of characters to a string.

char_list = ['h', 'e', 'l', 'l', 'o']
s = ''.join(char_list)  # Result: "hello"

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82

Swapping Case: Swap the case of all characters in a string.

s = "Hello World"
swapped = s.swapcase()  # Result: "hELLO wORLD"

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83

Using rjust() with Alignment: Right-align and pad with spaces or other characters.

s = "hello"
right_aligned = s.rjust(10, '-')  # Result: "-----hello"

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84

Formatting Numbers: Format numbers with specific precision.

number = 3.14159
formatted = "{:.2f}".format(number)  # Result: "3.14"

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85

Detecting Valid Identifiers: Check if a string is a valid Python identifier.

s = "my_variable"
is_identifier = s.isidentifier()  # Result: True

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86

Checking for Title Case: Check if a string is in title case.

s = "Hello World"
is_title = s.istitle()  # Result: True

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87

Converting to Raw String: Create a raw string where backslashes are treated literally.

s = r"hello\nworld"  # Result: "hello\nworld"

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88

Splitting with Multiple Delimiters: Split a string using multiple delimiters with regex.

import re
s = "a,b;c:d"
parts = re.split(r'[,\;:]', s)  # Result: ['a', 'b', 'c', 'd']

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89

Using lstrip() with Characters: Remove specific characters from the beginning of a string.

s = "000123"
stripped = s.lstrip('0')  # Result: "123"

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90

Using rstrip() with Characters: Remove specific characters from the end of a string.

s = "123000"
stripped = s.rstrip('0')  # Result: "123"

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