Yandex

Python BasicsPython Basics11
❯

  1. 1Introduction to Python
  2. 2Python Hello World Program
  3. 3Python Comments Explained - Beginner’s Guide with Examples
  4. 4Python Variables
  5. 5Python Constants
  6. 6Python Data Types
  7. 7Python Strings
  8. 8Python Type Conversions
  9. 9Python Basic Input and Output - Learn to Take User Input and Print Output
  10. 10Python Operators
  11. 11Python Operator Precedence – Evaluation Order with Examples

Python Flow ControlPython Flow Control5
❯

  1. 1Python Conditional Statements
  2. 2Python Loops
  3. 3Python For Loop
  4. 4Python While Loop
  5. 5Python Break and Continue

Python CollectionsPython Collections5
❯

  1. 1Introduction to Python Collections
  2. 2Python Lists
  3. 3Python Dictionaries
  4. 4Python Tuples
  5. 5Python Sets

Python FunctionsPython Functions4
❯

  1. 1Python Functions
  2. 2Python Functions with Parameters
  3. 3Python main() Function
  4. 4Python Lambda Functions

Python File HandlingPython File Handling1
❯

  1. 1Python File Operations – Read, Write, Update & Delete Files

Python Exception HandlingPython Exception Handling3
❯

  1. 1What Are Python Exceptions?
  2. 2Python Exception Handling
  3. 3Python Custom Exceptions

Python OOPsPython OOPs5
❯

  1. 1Python Object-Oriented Programming
  2. 2Python Inheritance
  3. 3Python Multiple Inheritance
  4. 4Python Encapsulation
  5. 5Python Polymorphism

Python Advanced ConceptsPython Advanced Concepts5
❯

  1. 1Python List Comprehension
  2. 2Python Iterators
  3. 3Python Generators
  4. 4Python Closures
  5. 5Python Decorators

Python LibrariesPython Libraries3
❯

  1. 1Python Email Tutorial
  2. 2Python JSON Tutorial – Parse, Read, Write & Handle JSON in Python
  3. 3Python datetime Tutorial - Working with Dates and Times in Python

Python ReferencePython Reference2
❯

  1. 1Python Built-in Functions
  2. 3Python String Methods

Python Built-in FunctionsPython Built-in Functions0
❯

    Python String MethodsPython String Methods0
    ❯

      ProgramGuru

      Python String index() Method – Find Position of a Substring

      Python String index() Method

      The index() method in Python is used to find the position of the first occurrence of a substring inside a string. If the substring is not found, it raises a ValueError.

      Syntax

      string.index(substring, start, end)

      Parameters:

      • substring – The string to search for.
      • start – (Optional) The position to start searching from. Default is 0.
      • end – (Optional) The position to stop searching. Default is end of the string.

      Returns:

      • The index (integer) of the first match of the substring.

      Example 1: Basic Usage

      text = "Python is fun"
print(text.index("fun"))
      10

      Explanation: The word "fun" starts at index 10 in the string.

      Example 2: With Start and End Parameters

      text = "banana"
print(text.index("a", 2))
      3

      Explanation: It starts searching from index 2, so it finds the second "a" at position 3.

      Difference Between index() and find()

      • index() raises a ValueError if the substring is not found.
      • find() returns -1 instead of raising an error.

      Common Error

      text = "hello"
print(text.index("z"))  # Raises ValueError
      ValueError: substring not found

      Use Case: Validate Substring Presence

      
text = "apple pie"
if "pie" in text:
    print("Found at index:", text.index("pie"))
      Found at index: 6

      Summary

      • string.index() returns the index of the first occurrence of a substring.
      • It raises a ValueError if not found.
      • Use optional start and end to limit the search range.

      Practice Problem

      Write a program to find the position of the word "world" in the string "hello world" using index().

      text = "hello world"
print("Index of 'world':", text.index("world"))

      Expected Output:

      6

      Next Steps

      Try using index() with different substrings and edge cases like empty strings or overlapping matches.

      Python String Methods❯

      1. 1Python String capitalize() – Capitalize First Letter of a String
      2. 2Python String casefold() – Case-Insensitive String Comparison
      3. 3Python String center() Method – Center Align a String with Padding
      4. 4Python String count() Method – Count Substring Occurrences
      5. 5Python string.encode() – Convert String to Bytes
      6. 6Python String endswith() – Check if a String Ends with Substring
      7. 7Python String expandtabs() – Replace Tabs with Spaces
      8. 8Python String find() – How to Locate Substrings Easily
      9. 9Python String index() Method – Find Position of a Substring
      10. 10Python String isalnum() Method – Check Alphanumeric Strings
      11. 11Python String isalpha() Method – Check for Alphabetic Characters
      12. 12Python String isascii() Method – Check for ASCII Characters
      13. 13Python String isdecimal() Method – Check if All Characters Are Decimals
      14. 14Python String isdigit() Method – Check If a String Has Only Digits
      15. 15Python String isidentifier() – Check for Valid Identifiers
      16. 16Python String islower() Method – Check for Lowercase Strings
      17. 17Python String isnumeric() Method – Check for Numeric Characters
      18. 18Python String isprintable() Method – Check Printable Characters
      19. 19Python String isspace() Method – Check for Whitespace Only
      20. 20Python String istitle() Method – Check for Title Case
      21. 21Python String isupper() Method – Check for Uppercase Letters
      22. 22Python String join() Method – Combine Strings Easily
      23. 23Python String ljust() Method – Left Justify a String with Spaces or Characters
      24. 24Python String lower() Method – Convert to Lowercase
      25. 25Python String lstrip() Method – Remove Leading Characters
      26. 26Python String maketrans() Method – Create Translation Tables
      27. 27Python String partition() Method – Split into Three Parts
      28. 28Python String replace() Method – Replace Substrings Easily
      29. 29Python String rfind() Method – Find Last Occurrence of Substring
      30. 30Python String rindex() Method – Find Last Occurrence of a Substring
      31. 31Python String rjust() Method – Right Justify a String
      32. 32Python String rpartition() Method – Split String from the Right
      33. 33Python String rsplit() Method – Split from the Right
      34. 34Python String rstrip() Method – Remove Trailing Characters
      35. 35Python String split() Method – Split Strings Easily
      36. 36Python String splitlines() Method – Split String by Line Breaks
      37. 37Python String startswith() Method – Check If a String Starts With
      38. 38Python String strip() Method – Remove Spaces from Ends
      39. 39Python String swapcase() Method – Convert Uppercase to Lowercase and Vice Versa
      40. 40Python String title() Method – Convert to Title Case
      41. 41Python String translate() Method – Replace Characters Using Mapping
      42. 42Python String upper() Method – Convert to Uppercase
      43. 43Python String zfill() Method – Pad String with Zeros

      Welcome to ProgramGuru

      Sign up to start your journey with us

      Support ProgramGuru.org❯

      You can support this website with a contribution of your choice.

      When making a contribution, mention your name, and programguru.org in the message. Your name shall be displayed in the sponsors list.

      PayPal

      UPI

      PhonePe QR

      MALLIKARJUNA M