scanf 后输入数字重置为 0

Question

我有一个奇怪的问题。我要求用户输入 1 到 15 之间的数字。然后我会询问用户是否愿意使用递归或 for 循环获取数字的阶乘值。当他们回答该问题时，输入的值变为 0。如果我出于测试目的删除问题，该值将保持用户输入的值。

#include <stdio.h>
    int recursive(int);
    int nonRecursive(int);
    
    int main() 
    {
      /* Variables */
      int numberSelected, returnedValue;
      char answer;
      
      do
      {
        /* Request a number between 1 and 15 */
        printf("Please enter a number between 1 and 15: ");
        scanf("%d", &numberSelected);
        printf("%d\n", numberSelected); /* This prints out the user's number */
      }while(numberSelected < 1 || numberSelected > 15); /* Loops if the value is not between 1 and 15 */
      
      /* Ask user if they want to return a recursive value or a value calculated manually */
      printf("Would you like a recusive value of the number you entered? Y or N: ");
      scanf("%s", &answer);
      if(answer == 'y' || answer == 'Y')
      {
        printf("%d\n", numberSelected); /* Here it resets to 0 */
        returnedValue = recursive(numberSelected); /* Returns the recursive value */
        printf("The recursive value of %d is %d\n", numberSelected, returnedValue);
      }
      else
      {
        printf("%d\n", numberSelected); /* Here it resets to 0 also*/
        returnedValue = nonRecursive(numberSelected); /* Returns the value from for loop */
        printf("The non recursive value of %d is %d\n", numberSelected, returnedValue);
      }
     
      
      return 0;
    }
    /* Get value using recursive */
    int recursive(int n)
    {
     if (n == 0)
     return 1; // Base case
     else
     return n * recursive(n - 1);
    }
    
    /* Get value using for loop */
    int nonRecursive(int n)
    {
      int i;
      int fact = 1;
      for(i = 1; i <= n; i++)
      {
         fact *= i;
      }
     
      return fact;
    }

感谢您的帮助

Answer 1

scanf("%s", &answer);

错了。 %s用于读取字符串（null-terminated sequence of characters），但是answer只有1个字符的空间，所以当读取一个或多个字符的字符串时会出现越界写。它可能会破坏相关数据。

该行应该是

scanf(" %c", &answer);

使用 %c，读取单个字符。
在 %c 之前添加 space 以使 scanf() 忽略白色 space 字符。

scanf 后输入数字重置为 0

Input number resets to 0 after scanf

c

printf

scanf