这个循环不符合条件时结束

Question

我想写一个程序来获取一个字符，然后检查并打印它是否使用大写或小写。然后，我希望它保持循环，直到用户输入一个应该产生消息的“0”。不起作用的是底部的条件，这个条件似乎从未得到满足。

#include <stdio.h> 
#include <stdlib.h> 

int main() 
{ 
    int ch,nope; // Int ch and nope variable used to terminate program 
    do  // start 'do' loop to keep looping until terminate number is entered 
    { 
     printf("Enter a character : ");    // asks for user input as a character 
     scanf("%c",&ch);       // stores character entered in variable 'ch' 
     if(ch>=97&&ch<=122) {      // starts if statement using isupper (in built function to check case) 
      printf("is lower case\n"); 
     } else { 
      printf("is upper case\n"); 
     } 
    } 
    while(ch!=0);          // sets condition to break loop ... or in this case print message 
    printf("im ending now \n\n\n\n\n",nope);  // shows that you get the terminate line 

} 

Answer 1

尝试while(ch!=48); 48为炭十进制数 '0'。正如Maroun Maroun所说，虽然（ch！='0'）;更容易理解。

如果你不想当用户输入一个“0”即可显示大写消息，你可以做这样的事情：

#include <stdio.h> 
#include <stdlib.h> 

int main() 
{ 
    unsigned char ch,nope; // Int ch and nope variable used to terminate program 
    while (1) 
    { 
     printf("Enter a character : ");    // asks for user input as a character 
     scanf("%c",&ch);       // stores character entered in variable 'ch' 
     if(ch==48) { 
      break; 
     } 
     if(ch>=97&&ch<=122) {      // starts if statement using isupper (in built function to check case) 
      printf("is lower case\n"); 
     } else { 
      printf("is upper case\n"); 
     } 

    } 
    printf("im ending now \n\n\n\n\n",nope);  // shows that you get the terminate line 

}