getchar_unlocked - Linux

Overview

getchar_unlocked is a C library function used for retrieving a single character from the standard input. It is primarily utilized in low-level input handling, especially when immediate and efficient character retrieval is required.

Syntax

#include <stdio.h>
int getchar_unlocked(void);

Options/Flags

getchar_unlocked does not take any options or flags.

Examples

Simple Input Handling:

int ch;
while ((ch = getchar_unlocked()) != EOF) {
  putchar_unlocked(ch);
}

Custom Input Validation:

int ch;
while ((ch = getchar_unlocked()) != EOF) {
  if (isalpha(ch)) {
    // Process alphabetic character
  }
}

Common Issues

Blocking Input:
getchar_unlocked blocks execution until a character is entered. This behavior can be problematic if you need to handle input from multiple sources or want to avoid blocking the thread.

Non-canonical Input:
getchar_unlocked reads characters in non-canonical mode, meaning it does not wait for a newline character to be entered. If you need to read a line of input, consider using fgets or getline.

Integration

Command Pipeline:
getchar_unlocked can be combined with other Linux commands using pipes to create versatile input handling pipelines:

command1 | grep "pattern" | getchar_unlocked

Command Substitution:
getchar_unlocked can be used in command substitution to capture user input and pass it as an argument to another command:

echo "Your name:"
value=$(getchar_unlocked)

Related Commands

• getchar: Similar to getchar_unlocked but blocks in canonical mode.
• fgets: Reads a line of input from standard input.
• getline: Similar to fgets but allows for more advanced input handling.