> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/python/cpython/llms.txt
> Use this file to discover all available pages before exploring further.

# io - Core I/O Operations

> Core tools for working with streams

The `io` module provides Python's main facilities for dealing with various types of I/O.

## Module Import

```python theme={null}
import io
```

## Text I/O

### StringIO - In-Memory Text Stream

```python theme={null}
import io

# Write to string buffer
output = io.StringIO()
output.write('Hello, ')
output.write('World!')
print(output.getvalue())  # 'Hello, World!'
output.close()

# Read from string buffer
input_stream = io.StringIO('Line 1\nLine 2\nLine 3')
for line in input_stream:
    print(line.strip())
```

## Binary I/O

### BytesIO - In-Memory Binary Stream

```python theme={null}
import io

# Write binary data
output = io.BytesIO()
output.write(b'Hello, ')
output.write(b'World!')
print(output.getvalue())  # b'Hello, World!'
output.close()

# Read binary data
input_stream = io.BytesIO(b'\x00\x01\x02\x03')
data = input_stream.read(2)
print(data)  # b'\x00\x01'
```

## File Objects

```python theme={null}
import io

# Open file in text mode
with io.open('file.txt', 'r', encoding='utf-8') as f:
    content = f.read()

# Open file in binary mode
with io.open('file.bin', 'rb') as f:
    data = f.read()
```

## Buffered I/O

```python theme={null}
import io

# Buffered reader
with io.open('large_file.txt', 'rb') as f:
    buffered = io.BufferedReader(f)
    chunk = buffered.read(1024)  # Read 1KB

# Buffered writer
with io.open('output.txt', 'wb') as f:
    buffered = io.BufferedWriter(f)
    buffered.write(b'Data to write')
    buffered.flush()
```

## Practical Examples

### Capture Print Output

```python theme={null}
import io
import sys

# Capture stdout
old_stdout = sys.stdout
sys.stdout = io.StringIO()

print("This goes to StringIO")
print("Another line")

output = sys.stdout.getvalue()
sys.stdout = old_stdout

print(f"Captured: {output}")
```

### Create File-Like Object from String

```python theme={null}
import io
import csv

# Use StringIO with csv module
csv_data = "name,age\nAlice,30\nBob,25"
string_io = io.StringIO(csv_data)

reader = csv.DictReader(string_io)
for row in reader:
    print(row)
```

<CardGroup cols={2}>
  <Card title="os" href="/library/os">
    Operating system interfaces
  </Card>

  <Card title="pathlib" href="/library/pathlib">
    Object-oriented filesystem paths
  </Card>
</CardGroup>