关于输入百分制成绩输出等级程序报错Run-Time Check Failure #3 - The variable ‘grade‘ is being used without being

答案很简单，我们这里列举一个最常见的方法

#include <stdio.h>
int main()
{
   
    int    data;          
    char  grade;                    
    printf("Please enter the score:");
    scanf("%d", &data);  
    switch(data/10)                   
    {
      case