C exit from infinite loop on keypress

How can I exit开发者_StackOverflow中文版 from an infinite loop, when a key is pressed? Currently I'm using getch, but it will start blocking my loop as soon, as there is no more input to read.

If you are using getch() from conio.h anyway, try to use kbhit() instead. Note that both getch() and kbhit() - conio.h, in fact - are not standard C.

The function kbhit() from conio.h returns non-zero value if any key is pressed but it does not block like getch(). Now, this is obviously not standard. But as you are already using getch() from conio.h, I think your compiler has this.

if (kbhit()) {
    // keyboard pressed
}

From Wikipedia,

conio.h is a C header file used in old MS-DOS compilers to create text user interfaces. It is not described in The C Programming Language book, and it is not part of the C standard library, ISO C nor is it required by POSIX.

Most C compilers that target DOS, Windows 3.x, Phar Lap, DOSX, OS/2, or Win321 have this header and supply the associated library functions in the default C library. Most C compilers that target UNIX and Linux do not have this header and do not supply the library functions.

I would suggest that you go throgh this article.

Non-blocking user input in loop without ncurses.

If you do not want to use non-standard, non-blocking way and yet graceful exit. Use signals and Ctrl+C with user provided signal handler to clean up. Something like this:

#include <stdio.h>
#include <signal.h>
#include <stdlib.h>

/* Signal Handler for SIGINT */
void sigint_handler(int sig_num)
{
    /* Reset handler to catch SIGINT next time.
       Refer http://en.cppreference.com/w/c/program/signal */
    printf("\n User provided signal handler for Ctrl+C \n");

    /* Do a graceful cleanup of the program like: free memory/resources/etc and exit */
    exit(0);
}

int main ()
{
    signal(SIGINT, sigint_handler);

    /* Infinite loop */
    while(1)
    {
        printf("Inside program logic loop\n");
    }
    return 0;
}

// Include stdlib.h to execute exit function
int char ch;
int i;

clrscr();
void main(){

printf("Print 1 to 5 again and again");
while(1){
for(i=1;i<=5;i++)

     printf("\n%d",i);

    ch=getch();
    if(ch=='Q')// Q for Quit
     exit(0);

    }//while loop ends here

    getch();
    }