String indexing allows you to access individual characters of a string using their position, or index.

Indexing in Python starts from `0`. That means the first character of any string has index `0`, the second character has index `1`, and so on.

For example, in the word `"codefinity"`:

To access a character by index, use square brackets `[]` with the index number inside:

string = "codefinity"

print("Print the c symbol:", string[0])  # First character
print("Print the o symbol:", string[1])  # Second character
print("Print the y symbol:", string[9])  # Last character

## Index Out of Range
If you try to access a character at an index that does not exist, Python will raise an error:

# This will raise an IndexError
string = "codefinity"
print(string[10])

This is called an "index out of range" error. In the word `"codefinity"`, valid indexes are from `0` to `9`, because it has `10` characters in total.

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

    def test_initial1_value(self):
        passed, result_text = self._test_variable_equals_string('initial1', 'M')
        self._testMethodName = result_text
        self.assertTrue(passed, result_text)

    def test_initial2_value(self):
        passed, result_text = self._test_variable_equals_string('initial2', 'J')
        self._testMethodName = result_text
        self.assertTrue(passed, result_text)

    def test_dot_value(self):
        passed, result_text = self._test_variable_equals_string('dot', '.')
        self._testMethodName = result_text
        self.assertTrue(passed, result_text)

    def test_output_contains_result_line(self):
        self._testMethodName = 'Program output contains "Result  : M.J."'
        import user_code
        saved_stdout = sys.stdout
        try:
            out = StringIO()
            sys.stdout = out
            exec(open("user_code.py").read())
            output_lines = out.getvalue().strip().splitlines()
            self.assertIn("Result  : M.J.", output_lines)
        finally:
            sys.stdout = saved_stdout

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.

String Indexing in Python

Index Out of Range

Solution