如何阻止用户在 C 中输入字符作为 int 输入 [英] How to stop user entering char as int input in C

问题描述

这是我的代码的一部分:

Heres a part of my code:

    printf("\nEnter amount of adult tickets:");
    scanf("%d", &TktAdult);
    while (TktAdult<0){
        printf("\nPlease enter a positive number!");
        printf("\nEnter amount of adult tickets:");
        scanf("%d", &TktAdult);
    }

现在它只能阻止用户输入负值，但我如何添加它以便它也阻止用户输入字符??

Right now it can only stop user from entering a negative value, but how do I add to it so it also stops user from entering a char??

推荐答案

以下代码拒绝用户输入:

The following code rejects user input that are:

• 由//1 处理的非数字；

• non-numeric as handled by // 1;

负数由//2 处理；

正数后跟由//3 处理的非数字字符

positive numbers followed by non-numeric chars as handled by //3

 while (1) {
     printf("\nEnter amount of adult tickets: ");
     if (scanf("%d", &TktAdult) < 0 ||  // 1
             TktAdult < 0 ||  // 2
             ((next = getchar()) != EOF && next != '\n')) {  // 3
         clearerr(stdin);
         do
             next = getchar();
         while (next != EOF && next != '\n');  // 4
         clearerr(stdin);
         printf("\nPlease enter a positive number!");
     } else {
         break;
     }
 }

此外，//4 清除标准输入的缓冲非数字字符//3(即 123sda - scanf 需要 123 但在缓冲区中留下 'sda').

Also, // 4 clears the standard input of buffered non-numeric characters following case // 3 (i.e. 123sda - scanf takes 123 but leaves 'sda' in the buffer).

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