scanf的返回值的用法
usage of the return value of scanf

我正在从一本书中学习C，我开始使用循环指令。 但是有一个我无法理解的示例代码。

任何人都可以告诉我为什么作者使用status = scanf("%ld", &num); ？ 为什么有一个= with scanf ？

/* summing.c -- sums integers entered interactively */
#include <stdio.h>
int main(void)
{
    long num;
    long sum = 0L; /* initialize sum to zero */
    int status;      
    printf("Please enter an integer to be summed ");
    printf("(q to quit): ");
    status = scanf("%ld", &num);
    while (status == 1) /* == means "is equal to" */
    {
        sum = sum + num;
        printf("Please enter next integer (q to quit): ");
        status = scanf("%ld", &num);
    }
    printf("Those integers sum to %ld.\n", sum);
    return 0;
}