How to Handle Input in Linux: An Alternative to kbhit() and getch()?

Input Handling in Linux: An Alternative to kbhit() and getch()

In Windows, _kbhit() and _getch() functions provide a simple way to check for keyboard input without halting the program. However, these functions are not available on Linux. This article explores an alternative approach for handling input on Linux.

Morgan Mattews's Code

One solution is to utilize the code provided by Morgan Mattews, which emulates the functionality of _kbhit() in a POSIX-compliant manner. It involves deactivating buffering at the termios level.

getchar() Issue

Disabling termios buffering not only addresses the _kbhit() absence but also tackles the getchar() issue by preventing input buffering.

Example

<code class="c">#include <stdio.h>
#include <termios.h>

int kbhit() {
    struct termios oldt, newt;
    int ch;
    int oldf;

    tcgetattr(STDIN_FILENO, &oldt);
    newt = oldt;
    newt.c_lflag &= ~(ICANON | ECHO);
    tcsetattr(STDIN_FILENO, TCSANOW, &newt);
    oldf = fcntl(STDIN_FILENO, F_GETFL, 0);
    fcntl(STDIN_FILENO, F_SETFL, oldf | O_NONBLOCK);

    ch = getchar();

    tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
    fcntl(STDIN_FILENO, F_SETFL, oldf);

    if (ch != EOF) {
        ungetc(ch, stdin);
        return 1;
    }

    return 0;
}

int main() {
    while (true) {
        if (kbhit()) {
            char c = getchar();
            if (c == 'g') {
                printf("You pressed G\n");
            }
        }
        printf("Running\n");
        sleep(1);
    }

    return 0;
}</code>

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