C non-blocking keyboard input

Question

I\'m trying to write a program in C (on Linux) that loops until the user presses a key, but shouldn\'t require a keypress to continue each loop.

Is there a simple wa

Answer 1

Here's a function to do this for you. You need termios.h which comes with POSIX systems.

#include 
void stdin_set(int cmd)
{
    struct termios t;
    tcgetattr(1,&t);
    switch (cmd) {
    case 1:
            t.c_lflag &= ~ICANON;
            break;
    default:
            t.c_lflag |= ICANON;
            break;
    }
    tcsetattr(1,0,&t);
}

Breaking this down: tcgetattr gets the current terminal information and stores it in t. If cmd is 1, the local input flag in t is set to non-blocking input. Otherwise it is reset. Then tcsetattr changes standard input to t.

If you don't reset standard input at the end of your program you will have problems in your shell.