C語言scanf的返回值

#include <stdio.h>
int main(void)
{
  long num;
  long sum = 0L;
  int status;

  printf("Please enter an integer to be summed");
  printf("(q to quit):");
  status = scanf("%ld",&num);
  while (status == 1)
  {
    sum = sum + num;
    printf("Please enter next integer to be summed(q to quit):");
    status = scanf("%ld",&num);
  }
  printf("Those integers sum to %ld.\n",sum);

  return 0 ;
}

scanf返回值：如果成功，該函數返回成功匹配和賦值的個數。如果到達文件末尾或發生讀錯誤，則返回 EOF。

while循環的判斷是status，當輸入的不是數字類型時，scanf會讀取失敗返回0。