Summary  
This chapter covers how to locate the position of a substring within a string using the `index()` method, showing its syntax and how it returns the first occurrence’s index.

General domain of usage  
Text processing

Hi there, it should be mentioned that there is another function that does the same action as `find()`, which is called `index()`.

Like `find()`, it returns the index of the first occurrence of a substring:

string = "I can manage everything"

manage = string.index('manage')
everything = string.index('everything')

print("The index of the word manage is", manage)
print("The index of the word everything is", everything)

The `index()` function has the following syntax:
```python
string.index('word')
```

The `index()` function returns the **first occurrence of the word** in the string, and the valuable point is that **it throws an exception if the word is not found**.

Definition

import importlib
import sys
from io import StringIO
import unittest


class TestUserCode(unittest.TestCase):

    def _test_variable_equals_value(self, var_name, expected):
        # Force local import and reload to prevent persistent module caching issues
        import user_code

        importlib.reload(user_code)

        if not hasattr(user_code, var_name):
            return (False, f"Expected '{var_name}' variable to be defined.")

        var = getattr(user_code, var_name)
        if var != expected:
            return (
                False,
                f"Expected '{var_name}' to equal {expected}, but got {var}.",
            )
        return (True, f"The variable {var_name} equals {expected}")

    def _assert_dynamic(self, var_name, expected):
        """Processes the validation and dynamically updates the test reporter name."""
        passed, result_text = self._test_variable_equals_value(
            var_name, expected
        )
        self._testMethodName = result_text
        self.assertTrue(passed, result_text)

    # --- Dynamic Test Cases ---

    def test_burning(self):
        self._assert_dynamic("burning", 21)

    def test_desire(self):
        self._assert_dynamic("desire", 29)

    def test_studying(self):
        self._assert_dynamic("studying", 40)


if __name__ == "__main__":
    unittest.main()

test_main.py

Gain a solid understanding of Python's core data types and learn how to work with them effectively. Explore numbers, booleans, and strings through hands-on exercises and practical examples. Build confidence in performing basic operations and develop the foundational skills needed to write clean and efficient Python code.

Discover the essentials of numerical data types in Python and learn how to work with integers and floating-point numbers. Master basic arithmetic operations, explore the concept of immutability, and get hands-on experience using Python's built-in functions and tools to handle numbers efficiently in real-world scenarios.

Gain a clear understanding of the Boolean data type, a specialized subtype of numeric data that represents truth values. Although it may seem challenging at first, mastering Booleans is essential for writing logical and efficient programs. This section will help you confidently apply Boolean logic to real-world programming scenarios.

Strings allow you to work with text in Python, from displaying messages to processing user input. You'll explore how to create, modify, and manipulate strings effectively. Understanding strings is essential for writing interactive programs and communicating information clearly through your code.

Learn how to handle data types effectively to ensure accuracy and consistency in your programs. Convert values to the appropriate type, clean text before comparison, and separate numeric operations from text formatting. You'll also discover how to manage missing data deliberately and handle human-readable text differently from raw input, achieving reliable, consistent, and easy-to-read results.

Find the Word Index

Solution