Struct std::io::Stdin

1.0.0 · source ·

pub struct Stdin { /* private fields */ }

Expand description

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(())
}

Run

Implementations

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impl Stdin

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pub fn lock(&self) -> StdinLock<'static>iNotable traits for StdinLock<'_>impl Read for StdinLock<'_>

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(())
}

Run

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

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.

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}"),
}

Run

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

1.62.0 · source

pub fn lines(self) -> Lines<StdinLock<'static>>iNotable traits for Lines<B>impl<B: BufRead> Iterator for Lines<B> type Item = Result<String>;

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());
}

Run

Trait Implementations

1.63.0 · source

impl AsFd for Stdin

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

Available on Unix only.

Borrows the file descriptor. Read more

1.63.0 · source

impl AsHandle for Stdin

Available on Windows only.

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fn as_handle(&self) -> BorrowedHandle<'_>

Borrows the handle. Read more

1.21.0 · source

impl AsRawFd for Stdin

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fn as_raw_fd(&self) -> RawFd

Available on Unix only.

Extracts the raw file descriptor. Read more

1.21.0 · source

impl AsRawHandle for Stdin

Available on Windows only.

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fn as_raw_handle(&self) -> RawHandle

Extracts the raw handle. Read more

1.16.0 · source

impl Debug for Stdin

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

Formats the value using the given formatter. Read more

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impl Read for Stdin

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

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

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

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

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fn is_read_vectored(&self) -> bool

🔬 This is a nightly-only experimental API. (can_vector #69941)

Determines if this Reader has an efficient read_vectored implementation. Read more

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

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

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

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

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

Read the exact number of bytes required to fill buf. Read more

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

🔬 This is a nightly-only experimental API. (read_buf #78485)

Pull some bytes from this source into the specified buffer. Read more

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fn read_buf_exact(&mut self, buf: &mut ReadBuf<'_>) -> Result<()>

🔬 This is a nightly-only experimental API. (read_buf #78485)

Read the exact number of bytes required to fill buf. Read more

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fn by_ref(&mut self) -> &mut Self where
Self: Sized,

Creates a "by reference" adaptor for this instance of Read. Read more

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fn bytes(self) -> Bytes<Self>iNotable traits for Bytes<R>impl<R: Read> Iterator for Bytes<R> type Item = Result<u8>; where
Self: Sized,

Transforms this Read instance to an Iterator over its bytes. Read more

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fn chain<R: Read>(self, next: R) -> Chain<Self, R>iNotable traits for Chain<T, U>impl<T: Read, U: Read> Read for Chain<T, U> where
Self: Sized,

Creates an adapter which will chain this stream with another. Read more

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fn take(self, limit: u64) -> Take<Self>iNotable traits for Take<T>impl<T: Read> Read for Take<T> where
Self: Sized,

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