> ## Documentation Index
> Fetch the complete documentation index at: https://python4ai.codewithsiva.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# String manipulation

> Advanced text operations

## Working with text

Now that you know what strings are, let's learn how to manipulate them. Python gives you powerful tools to work with text.

## String operations

### Concatenation (joining)

```python theme={null}
first_name = "Jane"
last_name = "Doe"

# Using +
full_name = first_name + " " + last_name  # "Jane Doe"

# Using f-strings (modern Python way!)
greeting = f"Hello, {first_name}!"  # "Hello, Jane!"

# Multiple variables
age = 25
intro = f"I'm {first_name} and I'm {age} years old"
```

### Repetition

```python theme={null}
star = "*"
stars = star * 10  # "**********"

separator = "-" * 20  # "--------------------"
```

## String methods

Python strings come with many built-in methods - functions you can call directly on any string. These methods let you transform text, search for patterns, and clean up data. The best part? You can often guess what they do from their names - `upper()` makes text uppercase, `replace()` replaces text, and so on.

### Changing case

```python theme={null}
text = "Python Programming"

print(text.lower())      # "python programming"
print(text.upper())      # "PYTHON PROGRAMMING"
print(text.title())      # "Python Programming"
```

### Cleaning strings

```python theme={null}
messy = "  hello world  "
print(messy.strip())     # "hello world" (removes whitespace)

price = "$19.99"
print(price.strip("$"))  # "19.99"
```

### Finding and replacing

```python theme={null}
message = "I love Python programming with Python"

# Check if something exists
print("Python" in message)        # True
print(message.startswith("I"))   # True
print(message.endswith("Python")) # True

# Find position
print(message.find("Python"))     # 7 (first occurrence)
print(message.count("Python"))    # 2 (number of times)

# Replace
new_message = message.replace("Python", "JavaScript")
print(new_message)  # "I love JavaScript programming with JavaScript"
```

<Note>
  Python has over 40 string methods! We've covered the most common ones here. For a complete list, check the [official Python documentation](https://docs.python.org/3/library/stdtypes.html#string-methods).
</Note>

## Common mistakes

<AccordionGroup>
  <Accordion title="Forgetting the f in f-strings">
    ```python theme={null}
    # Wrong
    name = "Alice"
    message = "Hello {name}"  # Prints: "Hello {name}"

    # Right
    message = f"Hello {name}"  # Prints: "Hello Alice"
    ```
  </Accordion>

  <Accordion title="Wrong quotes in strings">
    ```python theme={null}
    # Wrong - mismatched quotes
    text = 'It's Python'

    # Right - escape or use different quotes
    text = "It's Python"  # Double quotes outside
    text = 'It\'s Python'  # Escape the apostrophe
    ```
  </Accordion>
</AccordionGroup>

## What's next?

You've mastered working with data! Ready to make your programs smart with decision-making?

<Card title="Control flow" icon="code-branch" href="/control-flow">
  Learn if statements and loops
</Card>