// boolean.c -- using a _Bool variable
#include <stdio.h>

const char* PROMPT = "Please enter an integer to be summed. "
"Enter q to quit: ";

int main(void)
{
	long num;
	long sum = 0L;
	_Bool input_is_good;
	printf(PROMPT);
	input_is_good = (scanf("%ld", &num) == 1);
	while (input_is_good)
	{
		sum = sum + num;
		printf(PROMPT);
		input_is_good = (scanf("%ld", &num) == 1);
	}
	printf("Those integers sum to %ld.\n", sum);
	return 0;
}