Summary  
This chapter demonstrates using the string.find(substring) method to locate the index of the first occurrence of a given character or substring in a string, returning -1 if it’s not found.

General domain of usage  
Text processing

To find the index of a specific symbol or substring in a string, Python provides the built-in `.find()` method. This method returns the index of the first occurrence of the substring. If the substring is not found, it returns -1.

```python
string.find(substring)
```
Here, string is the original text, and substring is the character or sequence you want to locate.

string = "Channel efforts to success!"
print(string.find('n'))

In the string `"Channel efforts to success!"`, the first `'n'` appears at index 3. So, the `find()` method returns 3.

If the character were not found, for example, `string.find('z')`, the result would be -1.

import unittest
import sys
from io import StringIO


class TestUserCode(unittest.TestCase):
    def _test_variable_equals_string(self, var_name, expected):
        import 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 test_p(self):
        passed, result_text = self._test_variable_equals_string(
            'p', 15)
        self._testMethodName = result_text
        self.assertTrue(passed, result_text)

    def test_y(self):
        passed, result_text = self._test_variable_equals_string(
            'y', 5)
        self._testMethodName = result_text
        self.assertTrue(passed, result_text)

    def test_r(self):
        passed, result_text = self._test_variable_equals_string(
            'r', 2)
        self._testMethodName = result_text
        self.assertTrue(passed, result_text)


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


test_main.py

This course is going to help you dive deeper into data types and try to work with them. Here you will learn basic operations and all ins and outs of numbers, boolean data type, and strings. This course consists of a lot of practical tasks after which you will become a skillful programmer.

Numeric data types are crucial in Python, so it is important to start with them. Here you will work with simple math operations and find out the purposes of learning different types of numerical data.

Mastering boolean data types and logical operations in Python. You'll learn how to work with True and False, apply logical operators like and, or, and not, and understand how operator precedence works in complex expressions.

Strings are an essential part of Python programming, allowing you to work with text data. In this section, you'll learn how to manipulate strings, extract characters, slice words, and search for specific phrases.

This chapter consists of practical tasks that combine all the examined topics together with a bit of theory.

Get the Index of the Symbol

Solution

Awesome!

Get the Index of the Symbol

Solution

Awesome!

Get the Index of the Symbol

Solution