stderr in std::io - Rust
Description: Constructs a new handle to the standard error of the current process.

## stderr

# Function stderr

1.0.0 · Source

    pub fn stderr() -> Stderr ⓘ

Expand description

Constructs a new handle to the standard error of the current process.

This handle is not buffered.

#### §Note: Windows Portability Considerations

When operating in a console, the Windows implementation of this stream does not support non-UTF-8 byte sequences. Attempting to write bytes that are not valid UTF-8 will return an error.

In a process with a detached console, such as one using `#![windows_subsystem = "windows"]`, or in a child process spawned from such a process, the contained handle will be null. In such cases, the standard library’s `Read` and `Write` will do nothing and silently succeed. All other I/O operations, via the standard library or via raw Windows API calls, will fail.

## §Examples

Using implicit synchronization:

    use std::io::{self, Write};

    fn main() -> io::Result<()> {
        io::stderr().write_all(b"hello world")?;

        Ok(())
    }

Using explicit synchronization:

    use std::io::{self, Write};

    fn main() -> io::Result<()> {
        let stderr = io::stderr();
        let mut handle = stderr.lock();

        handle.write_all(b"hello world")?;

        Ok(())
    }