Python String index() Method Last Updated : 02 May, 2025 Comments Improve Suggest changes Like Article Like Report The index() method in Python is used to find the position of a specified substring within a given string. It is similar to the find() method but raises a ValueError if the substring is not found, while find() returns -1. This can be helpful when we want to ensure that the substring exists in the string before proceeding. Let's see a simple use of index(): Python s = "Python programming" p = s.index("prog") print(p) Output7 Explanation: index() method searches for the substring "prog" within "Python programming" and returns starting index 7.Syntax of index()s.index(substring, start=0, end=len(s))Parameters:substring: The substring to locate within the string s.start (optional): The starting index for the search. Defaults to 0 if not provided.end (optional): The ending index for the search. If not provided, it defaults to the length of the string.Return Type:Returns the lowest index of the substring if found in the given string.Raises a ValueError if the substring is not found in the specified range.Example of index() MethodLet's understand the use of index() with the help of some examples.Example 1: Using index() with only substring argumentThis code demonstrates how to find the index of a substring within a string using the index() method. Python s = "Python programming is powerful" p = s.index("programming") print(p) Output7 Explanation:Here, we only provide the substring argument "programming".index() searches from the start of the string and finds "programming" at index 7, which it returns.Example 2: Using index() with substring, start and end argumentsThis code demonstrates how to find the index of a substring within a specific range of a string using the index() method with optional start and end parameters. Python s = "Python programming is fun" p = s.index("is", 10, 25) print(p) Output19 Explanation:We specify start=10 and end=25, so index() searches between these positions.It finds "is" at index 18 within this range and returns 18.Related Articles:Python String find() MethodPython String rindex() MethodPython String rfind() Method Comment More infoAdvertise with us Next Article String capitalize() Method in Python M manjeet_04 Follow Improve Article Tags : Python Python-Built-in-functions python-string Practice Tags : python Similar Reads Python String Methods Python string methods is a collection of in-built Python functions that operates on strings.Note: Every string method in Python does not change the original string instead returns a new string with the changed attributes. Python string is a sequence of Unicode characters that is enclosed in quotatio 5 min read String capitalize() Method in Python The capitalize() method in Python is used to change the first letter of a string to uppercase and make all other letters lowercase. It is especially useful when we want to ensure that text follows title-like capitalization, where only the first letter is capitalized.Let's start with a simple example 2 min read Python String casefold() Method Python String casefold() method is used to convert string to lowercase. It is similar to the Python lower() string method, but the case removes all the case distinctions present in a string. Python String casefold() Method Syntax Syntax: Â string.casefold() Parameters: The casefold() method doesn't t 1 min read Python String center() Method center() method in Python is a simple and efficient way to center-align strings within a given width. By default, it uses spaces to fill the extra space but can also be customized to use any character we want. Example:Pythons1 = "hello" s2 = s1.center(20) print(s2)Output hello Explanation: Here, the 2 min read Python String count() Method The count() method in Python returns the number of times a specified substring appears in a string. It is commonly used in string analysis to quickly check how often certain characters or words appear.Let's start with a simple example of using count().Pythons = "hello world" res = s.count("o") print 2 min read Python - Strings encode() method String encode() method in Python is used to convert a string into bytes using a specified encoding format. This method is beneficial when working with data that needs to be stored or transmitted in a specific encoding format, such as UTF-8, ASCII, or others.Let's start with a simple example to under 3 min read Python String endswith() Method The endswith() method is a tool in Python for checking if a string ends with a particular substring. It can handle simple checks, multiple possible endings and specific ranges within the string. This method helps us make our code cleaner and more efficient, whether we're checking for file extensions 2 min read expandtabs() method in Python expandtabs() method in Python is used to replace all tab characters (\t) in a string with spaces. This method allows for customizable spacing, as we can specify the number of spaces for each tab. It is especially useful when formatting text for better readability or alignment. Let's understand with 3 min read Python String find() Method find() method in Python returns the index of the first occurrence of a substring within a given string. If the substring is not found, it returns -1. This method is case-sensitive, which means "abc" is treated differently from "ABC". Example:Pythons = "Welcome to GeekforGeeks!" index = s.find("Geekf 2 min read Python String format() Method format() method in Python is a tool used to create formatted strings. By embedding variables or values into placeholders within a template string, we can construct dynamic, well-organized output. It replaces the outdated % formatting method, making string interpolation more readable and efficient. E 8 min read Like