如何在c中检查字符串是否为字母（a-z或A-Z） [英] How to check if a string is a letter(a-z or A-Z) in c

问题描述

我正在获得用户输入，我想确定用户是否输入了字母，整数或运算符。我可以使用sscanf成功地确定它是否是整数，但是我对如何确定它是否是一个字母感到困惑。

I am getting user input, and I want to determine if the user has entered a letter , an integer, or an operator. I can successfully determine if it is an integer using sscanf, but I am stumped on how to determine if it is a letter.

按字母表示，我的意思是：AZ，az 。

By letter, I mean: A-Z, a-z.

int main(){
    char buffer[20];
    int integer; 
    printf("Enter expression: ");
    while (fgets(buffer, sizeof(buffer), stdin) != NULL){
        char *p = strchr(buffer, '\n'); //take care of the new line from fgets
        if (p) *p = 0;

        //Buffer will either be a integer, an operator, or a variable (letter).
        //I would like a way to check if it is a letter
        //I am aware of isalpha() but that requires a char and buffer is a string

         //Here is how I am checking if it is an integer
         if (sscanf(buffer, "%d", &integer) != 0){
             printf("Got an integer\n");
         }
         else if (check if letter)
             // need help figuring this out
         } 
         else{
             // must be an operator
         }
    }
}

推荐答案

您可以使用 isalpha（）和 isdigit（）标准函数。只需包含< ctype.h> 。

You can use the isalpha() and isdigit() standard functions. Just include <ctype.h>.

     if (isdigit(integer)) != 0){
         printf("Got an integer\n");
     }
     else if (isalpha(integer))
         printf"Got a char\n"); 
     } 
     else{
         // must be an operator 
     }

这篇关于如何在c中检查字符串是否为字母（a-z或A-Z）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！