Struct Stdin

pub struct Stdin { /* private fields */ }

A handle to the standard input stream of a process.

Each handle is a shared reference to a global buffer of input data to this process. A handle can be lock’d to gain full access to BufRead methods (e.g., .lines()). Reads to this handle are otherwise locked with respect to other reads.

This handle implements the Read trait, but beware that concurrent reads of Stdin must be executed with care.

Created by the io::stdin method.

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 read 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

use std::io;

fn main() -> io::Result<()> {
    let mut buffer = String::new();
    let stdin = io::stdin(); // We get `Stdin` here.
    stdin.read_line(&mut buffer)?;
    Ok(())
}

Implementations

impl Stdin

pub fn lock(&self) -> StdinLock<'static>

Locks this handle to the standard input stream, returning a readable guard.

The lock is released when the returned lock goes out of scope. The returned guard also implements the Read and BufRead traits for accessing the underlying data.

Examples

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

fn main() -> io::Result<()> {
    let mut buffer = String::new();
    let stdin = io::stdin();
    let mut handle = stdin.lock();

    handle.read_line(&mut buffer)?;
    Ok(())
}

pub fn read_line(&self, buf: &mut String) -> Result<usize, Error>

Locks this handle and reads a line of input, appending it to the specified buffer.

For detailed semantics of this method, see the documentation on BufRead::read_line. In particular:

• Previous content of the buffer will be preserved. To avoid appending to the buffer, you need to clear it first.
• The trailing newline character, if any, is included in the buffer.

Examples

use std::io;

let mut input = String::new();
match io::stdin().read_line(&mut input) {
    Ok(n) => {
        println!("{n} bytes read");
        println!("{input}");
    }
    Err(error) => println!("error: {error}"),
}

You can run the example one of two ways:

• Pipe some text to it, e.g., printf foo | path/to/executable
• Give it text interactively by running the executable directly, in which case it will wait for the Enter key to be pressed before continuing

pub fn lines(self) -> Lines<StdinLock<'static>>

Consumes this handle and returns an iterator over input lines.

For detailed semantics of this method, see the documentation on BufRead::lines.

Examples

use std::io;

let lines = io::stdin().lines();
for line in lines {
    println!("got a line: {}", line.unwrap());
}

Trait Implementations

impl AsFd for Stdin

fn as_fd(&self) -> BorrowedFd<'_>

Borrows the file descriptor.

impl AsRawFd for Stdin

fn as_raw_fd(&self) -> i32

Extracts the raw file descriptor.

impl Debug for Stdin

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl IsTerminal for Stdin

fn is_terminal(&self) -> bool

Returns true if the descriptor/handle refers to a terminal/tty.

impl IsTerminal for Stdin

fn is_terminal(&self) -> bool

Returns true if the descriptor/handle refers to a terminal/tty.

impl Read for &Stdin

fn read(&mut self, buf: &mut [u8]) -> Result<usize, Error>

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf)

Pull some bytes from this source into the specified buffer.

fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize, Error>

Like read, except that it reads into a slice of buffers.

fn is_read_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)

Determines if this Reader has an efficient read_vectored implementation.

fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize, Error>

Reads all bytes until EOF in this source, placing them into buf.

fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>

Reads all bytes until EOF in this source, appending them to buf.

fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

Reads the exact number of bytes required to fill buf.

fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf)

Reads the exact number of bytes required to fill cursor.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adaptor for this instance of Read.

fn bytes(self) -> Bytes<Self>

where Self: Sized,

Transforms this Read instance to an Iterator over its bytes.

fn chain<R>(self, next: R) -> Chain<Self, R>

where R: Read, Self: Sized,

Creates an adapter which will chain this stream with another.

fn take(self, limit: u64) -> Take<Self>

where Self: Sized,

Creates an adapter which will read at most limit bytes from it.

impl Read for Stdin

fn read(&mut self, buf: &mut [u8]) -> Result<usize, Error>

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf)

Pull some bytes from this source into the specified buffer.

fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize, Error>

Like read, except that it reads into a slice of buffers.

fn is_read_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)

Determines if this Reader has an efficient read_vectored implementation.

fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize, Error>

Reads all bytes until EOF in this source, placing them into buf.

fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>

Reads all bytes until EOF in this source, appending them to buf.

fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

Reads the exact number of bytes required to fill buf.

fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf)

Reads the exact number of bytes required to fill cursor.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adaptor for this instance of Read.

fn bytes(self) -> Bytes<Self>

where Self: Sized,

Transforms this Read instance to an Iterator over its bytes.

fn chain<R>(self, next: R) -> Chain<Self, R>

where R: Read, Self: Sized,

Creates an adapter which will chain this stream with another.

fn take(self, limit: u64) -> Take<Self>

where Self: Sized,

Creates an adapter which will read at most limit bytes from it.