使用_bool变量

#include <stdio.h>
#include <stdbool.h>

int main(void){
    long num;
    long sum = 0L;
    bool input_is_good;

    printf(Please enter an integer to be summed );
    printf((q to quit): );
    input_is_good = (scanf(%ld, &num) == 1);

    while (input_is_good){
        sum = sum + num;
        printf(Please enter next integer (q to quit): );
        input_is_good = (scanf(%ld, &num) == 1);
    }
    printf(sum: %ld.\n, sum);

    return 0;
}