如何验证小写和大写字母 [英] how to validate both lowercase and uppercase letters

问题描述

下面我写了一个评估字母等级的程序，并根据分数的不同打印一条消息。假设我想从用户输入中获取该信息，我如何能够接受大写和小写字母？

Below I have written a program to evaluate a letter grade and print a message based on how well the score is. Let's say I wanted to get that information from the user input, how would I be able to accept both lower and upper case letters?

 #include <stdio.h>
 int main (){
     /* local variable definition */
     char grade = 'B';

     if (grade == 'A'){ 
         printf("Excellent!\n");
     }
     else if (grade == 'B' || grade == 'C'){
         printf("Well done\n");
     }
     else if (grade == 'D'){
         printf("You passed\n" );
     }
     else if (grade == 'F'){
         printf("Better try again\n" );
     }
     else {
         printf("Invalid grade\n" );
     }
     printf("Your grade is %c\n", grade );
     return 0;
 }

推荐答案

我如何能够接受大写和小写字母？

how would i be able to accept both lower and upper case letters?

你想要标准化年级使用 toupper（） 在执行支票之前。

You want to normalize grade using toupper() before performing the checks.

您还可以使用 switch（）语句如

 switch(toupper(grade)) {
 case 'A':
      // ...
     break;
 case 'B':
 case 'C': // Match both 'B' and 'C'
      // ...
     break;
 }

---

更难的方法是检查小写：

---

The harder way is to check for lower case as well:

 if (grade == 'A' || grade == 'a'){ 
    // ...
 }
 else if (grade == 'B' || grade == 'b' || grade == 'C' || grade == 'c'){
    // ...
 }
 // ...

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