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# Example 1: Writing to a file (overwrites if it exists)
with open("message.txt", "w") as file:
    file.write("Hello!\nWelcome to Python file handling.")

print("File 'message.txt' has been written.")

# Separator line
print('=' * 40)

# Example 2: Appending to the same file
with open("message.txt", "a") as file:
    file.write("\nThis line was added later.")

print("Appended new line to 'message.txt'.")

# Separator line
print('=' * 40)

# Example 3: Reading the file content
with open("message.txt", "r") as file:
    content = file.read()
    print("File contents:\n", content)

# File Reading and Writing (Text Files)

Python allows you to read from and write to text files using the built-in `open()` function.

This is useful when you want to save data to a file or load data from one.

 

## 1. Opening a File

Use `open(filename, mode)` to access a file.

- `"r"` = read (default)
- `"w"` = write (overwrites file)
- `"a"` = append (adds to the end)
- `"x"` = create (fails if file exists)

Always **close** the file after using it, or use a `with` block.

 

## 2. Reading a File

```python
with open("greeting.txt", "r") as file:
 content = file.read()
 print(content)
```

*Explanation:*

* `with` ensures the file closes automatically.
* `file.read()` reads the entire file content as a string.

 

## 3. Writing to a File

```python
with open("note.txt", "w") as file:
 file.write("This is a new line.")
```

*Explanation:*

* `"w"` mode creates the file or overwrites it.
* Use `file.write()` to add content.

 

## 4. Appending to a File

```python
with open("note.txt", "a") as file:
 file.write("\nThis line is added.")
```

*Explanation:*

* `"a"` mode adds new content without deleting existing data.

 

## Summary

| Mode | Description |
| ----- | ------------------------------- |
| `"r"` | Read only |
| `"w"` | Write (overwrite) |
| `"a"` | Append to file |
| `"x"` | Create file, error if it exists |

 

## What’s Next?

Next, you’ll learn how to **work with CSV files**, which are commonly used to store structured data like spreadsheets.

The 'with' block simplifies file handling by ensuring the file is closed automatically after the block's execution. This helps prevent resource leaks and makes the code cleaner and less error-prone.

### How do you automatically ensure a file is closed after reading its contents in Python?

Mode	Description
`"r"`	Read only
`"w"`	Write (overwrite)
`"a"`	Append to file
`"x"`	Create file, error if it exists