c - 每次输入一个单词，这个单词的字母数量就会在c中打印很多次的错误信息

Question

对从哪里开始解决这个问题有点困惑。例如，如果我运行该程序，当它要求输入正数时，我会输入“kobe”，错误消息将显示4次，“我很抱歉......”等等。

 #include<stdio.h>

 int main(int agrc, char * argv[]) {
      int sum = 0, num, c;
      printf("Please enter a positive integer: \n");
      scanf_s("%d", &num);
      scanf_s("%c", &c);

      do  
      {  
           sum = num;
           if (num <= 0) {
               printf("I'm sorry, you must enter an integer greater than zero: \n");
               scanf_s("%d", &num);
               scanf_s("%c", &c);
          }

    } while (num <= 0);

    printf("The positive integer was: %d\n", sum);

    return 0;
}

Answer 1

检查scanf_s的返回值以确保输入操作确实成功(即用户输入了十进制整数):

num = 0;
while ( num <= 0 )
{
  printf("Please enter a positive integer: \n");
  if ( scanf_s( "%d", &num ) == 0 )
  {
    /**
     * A return value of 0 means the user typed in something
     * that isn't a decimal integer; clear out the input
     * stream and try again.
     */
    while ( getchar() != '\n' )
      ; // empty loop
  }
}