Take input in an infinte loop in c - c

Question

I am writing a C program to blink LED for Raspberry Pi. Its like (i) Blink LED (2) Stop blinking it.
Now while the LED is blinking, if I press 2 it should stop blinking. How to do it ?
If I include scanf inside the code will stop blinking.
while(1)
{
printf("Enter a command \n 1.Blink Led\n 2. Stop blinking\n");
scanf("%d",&choice);
if(choice==1)
for (;;)
{
digitalWrite (LED, HIGH) ; // On
delay (500) ; // mS
digitalWrite (LED, LOW) ; // Off
delay (500) ;
// If i press 2 the led should stop blinking
}
else if(choice==2){
digitalWrite (LED, LOW) ;
}

Answer 1

if you don't want to interrupt the Blinking you should try to run the blinking in a parallel process using pthread_t.
i really want to give you the code but i'm not on my PC at the moment.

Answer 2

Use poll:
#include <stdio.h>
#include <unistd.h>
#include <poll.h>
int main()
{
struct pollfd mypoll = { STDIN_FILENO, POLLIN|POLLPRI };
unsigned char c, blink=1, on =1, q=1;
while(q) {
if( poll(&mypoll, 1, 500) ) {
c=getchar();
switch(c) {
case '1':
blink = 1;
break;
case '2':
blink =0;
break;
case 'q':
q= 0;
break;
}
}
else{
if (blink) {
if (on)
on =0;
else
on =1;
}
printf("%u\n",on);
}
}
return 0;
}
replace the on parameter with the led functions.