Python String Methods

Python provides a variety of built-in string methods that allow you to manipulate and format strings in many ways. Each method returns a new string; the original string remains unchanged.

Here’s an overview of some common string methods:

1. capitalize()

Converts the first character of the string to uppercase.

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text = "hello world"
print(text.capitalize())  # Output: "Hello world"

2. casefold()

Converts the string to lowercase, more aggressive than lower(), useful for case-insensitive comparisons.

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text = "HELLO"
print(text.casefold())  # Output: "hello"

3. center()

Centers the string, padding it with spaces or a specified character.

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text = "Hello"
print(text.center(10, '*'))  # Output: "**Hello***"

4. count()

Counts how many times a substring appears in a string.

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text = "banana"
print(text.count('a'))  # Output: 3

5. encode()

Encodes the string using the specified encoding (default is UTF-8).

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text = "Hello"
print(text.encode())  # Output: b'Hello' (in bytes)

6. endswith()

Checks if the string ends with a specified suffix.

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text = "hello.txt"
print(text.endswith('.txt'))  # Output: True

7. find()

Finds the first occurrence of a substring and returns its position. Returns -1 if not found.

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text = "Hello World"
print(text.find("World"))  # Output: 6

8. format()

Inserts variables into a string using placeholders.

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name = "John"
age = 30
print("My name is {} and I am {} years old.".format(name, age))  # Output: My name is John and I am 30 years old.

9. isalnum()

Returns True if the string consists only of alphanumeric characters (letters and numbers).

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text = "Hello123"
print(text.isalnum())  # Output: True

10. isalpha()

Returns True if the string consists only of alphabetic characters.

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text = "Hello"
print(text.isalpha())  # Output: True

11. islower()

Checks if all characters in the string are lowercase.

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text = "hello"
print(text.islower())  # Output: True

12. join()

Joins elements of an iterable (such as a list) into a single string, with a specified separator.

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list_of_words = ['Hello', 'World']
print(" ".join(list_of_words))  # Output: "Hello World"

13. replace()

Replaces occurrences of a substring with another string.

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text = "Hello World"
print(text.replace("World", "Universe"))  # Output: "Hello Universe"

14. split()

Splits the string at the specified separator and returns a list.

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text = "apple,banana,grape"
print(text.split(','))  # Output: ['apple', 'banana', 'grape']

15. strip()

Removes leading and trailing whitespace or specified characters.

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text = "  Hello World  "
print(text.strip())  # Output: "Hello World"

16. upper()

Converts the string to uppercase.

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text = "hello"
print(text.upper())  # Output: "HELLO"

17. title()

Converts the first character of each word to uppercase.

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text = "hello world"
print(text.title())  # Output: "Hello World"

18. zfill()

Fills the string with leading zeros until it reaches a specified length.

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text = "42"
print(text.zfill(5))  # Output: "00042"