String Methods in python

Vinod Gosala

4 min read

·

Jun 23, 2026

--

Listen

Share

• upper() : Converts all lowercase letters to UPPERCASE. (Non-alphabets are completely ignored).
• lower():Converts all uppercase letters to lowercase.
• title() :Capitalizes the First Letter Of Every Word.
• capitalize() :Capitalizes only the very first letter of the entire string.
• swapcase(): Swaps the case (UPPER → lower, and lower →$ UPPER).
• strip() Cuts out all spaces from both the left (start) and right (end) sides.
• lstrip() :Cuts out spaces from the Left side only.
• rstrip() :Cuts out spaces from the Right side only.
• count(substring) :Counts how many times a character/pattern appears.
• find(substring) :Returns the lowest index address. Returns -1 if the character is not found.
• index(substring) :Exactly like find(), but crashes with a ValueError if not found.
• split(separator): Breaks a single string into a List of multiple strings based on a separator.
• replace(old, new) :Swaps an old character/pattern with a brand new one.
• isalpha() :True if it contains only alphabets (No spaces allowed!).
• isdigit() :True if it contains only numbers (0-9).
• isalnum() :True if it is a mix of only alphabets and numbers.
• islower() :True if all letters are lowercase.
• isupper() :True if all letters are uppercase.

partition(substring)

• Always cuts the string into exactly 3 parts based on your split value.
• Layout: (before, split_value, after)

center(len, ch)

• Shifts the string right to the center of a new line.
• Layout: Fills left and right sides with your custom character (ch)

zfill(len)

• Pads your data with leading zeros (0) on the left side.
• Layout: Stops filling once the total length matches your len number.

str.maketrans("input", "output")

• Creates a mapping table (dictionary) that connects the ASCII values of your input characters to your output characters.
• Rule: The input and output strings must have the same length

Var.translate(mapping_table)

• Uses the mapping table to actually swap out characters in your string.
• Rule: Can be used on any string to perform character translation

isupper()

• Checks whether all the characters inside a string are in uppercase.
• Rule: Returns True if all letters are capital; otherwise False.

. islower()

• Checks whether all the characters inside a string are in lowercase.

.️⃣ istitle()

• Checks every single word in the string.
• Rule: Returns True if the 1st letter of every word is uppercase and the remaining letters are lowercase.

. isdigit()

• Returns True if all the elements in the string are numbers (0-9). Otherwise, returns False.

. isalpha()

• Returns True if all the elements in the string are alphabets (a-z, A-Z). (No spaces or numbers allowed!)

. isalnum()

• Returns True if the string contains a clean mix of only alphabets, only digits, or both (no special characters like @, #, or spaces).

isspace()

• Checks if the string contains only whitespace characters (spaces, tabs, or newlines).
• Output: Returns True if it is completely empty space; otherwise False.

. isidentifier()

• Checks whether a string can be used as a valid Variable Name / Identifier according to Python’s naming conventions.
• Rule: Returns True if it only contains letters, numbers, and underscores, and does not start with a number.

. startswith(substring)

• Checks if a string sequence begins with a specific character or phrase.
• Output: Returns True if the prefix matches; otherwise False.

. endswith(substring)

• Checks if a string sequence finishes with a specific character or phrase.
• Output: Returns True if the suffix matches; otherwise False

isspace()

• In Short: Checks if the string contains only whitespace characters (spaces, tabs, or newlines).
• Output: Returns True if it is completely empty space; otherwise False.

. isidentifier()

• Checks whether a string can be used as a valid Variable Name / Identifier according to Python’s naming conventions.
• Rule: Returns True if it only contains letters, numbers, and underscores, and does not start with a number.

. startswith(substring)

• Checks if a string sequence begins with a specific character or phrase.
• Output: Returns True if the prefix matches; otherwise False.

. endswith(substring)

• Checks if a string sequence finishes with a specific character or phrase.
• Output: Returns True if the suffix matches; otherwise False

. isspace()

• Checks if the string contains only whitespace characters (spaces, tabs, or newlines).
• Output: Returns True if it is completely empty space; otherwise False.

. isidentifier()

• Checks whether a string can be used as a valid Variable Name / Identifier according to Python’s naming conventions.
• Rule: Returns True if it only contains letters, numbers, and underscores, and does not start with a number.

. startswith(substring)

• Checks if a string sequence begins with a specific character or phrase.
• Output: Returns True if the prefix matches; otherwise False.

. endswith(substring)

• Checks if a string sequence finishes with a specific character or phrase.
• Output: Returns True if the suffix matches; otherwise False.