Question

I want a infinit loop to break when I press “q” key on my keyboard.
Problems I did’nt realize: standard getchar waits for the user to make an
input and press enter, which halt the execution of the loop there.

I got around the “enter” problem, but the loop still halts and waits for the input.

here is my code:

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <termios.h>

int getch(void); // Declare of new function

int main (void) { char x;

do 
{ 
   if (x = getch())
      printf ("Got It! \n!); 
   else 
   { 
      delay(2000);
      printf ("Not yet\n!); 
   }

}while x != 'q');

return 0;
}


int getch(void)
{
int ch;
struct termios oldt;
struct termios newt;

tcgetattr(STDIN_FILENO, &oldt);
newt = oldt;
newt.c_lflag &= ~(ICANON | ECHO);
tcsetattr(STDIN_FILENO, TCSANOW, &newt);
ch = getchar();
tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
return ch;
}

Answer 1

I had to do following to make it work correctly, thanks for input!!

#include <stdio.h> 
#include <stdlib.h> 
#include <stdint.h> 
#include <unistd.h> 
#include <termios.h> 
#include <fcntl.h>

int getch(void); // Declare of new function 

int main (void) 
{ 

char x; 

do  
{  
x = getch();
        if (x != EOF)
        {
            printf ("\r%s\n", "Got something:");
            printf ("it's %c!",x); //  %c - for character %d - for ascii number   
}else  
   {  
      delay(2000); 
      printf ("Not yet\n!);  
   } 

}while x != 'q'); 

return 0; 
} 


int getch(void)
{
    int ch;
    struct termios oldt;
    struct termios newt;
    long oldf;
    long newf;

    tcgetattr(STDIN_FILENO, &oldt);             /* Store old settings */
    newt = oldt;
    newt.c_lflag &= ~(ICANON | ECHO);           /* Make one change to old settings in new settings */
    tcsetattr(STDIN_FILENO, TCSANOW, &newt);    /* Apply the changes immediatly */

    oldf = fcntl(STDIN_FILENO, F_GETFL, 0);
    newf = oldf | O_NONBLOCK;
    fcntl(STDIN_FILENO, F_SETFL, newf);

    ch = getchar();
    fcntl(STDIN_FILENO, F_SETFL, oldf);
    tcsetattr(STDIN_FILENO, TCSANOW, &oldt);    /* Reapply the old settings */
    return ch;
}