如何将整数的输入限制为仅2-12? [英] How to limit an integer's input to 2-12 only?

问题描述

我想严格限制用户在此程序中输入的整数只能为2-12.我该怎么办?

I want to strictly limit a user's input on an integer in this program to 2-12 only. How do I do that?

#include <stdio.h>

int main(){
    int i;
    scanf("%d", &i);
    int diceThrown, diceResult;
    int sum = 0; 
    for(diceThrown = 1; diceThrown <= i; diceThrown++){
        scanf("%d", &diceResult);   //limit this input to 2-12 only, how?
        sum += diceResult;
    }
    if(sum >= 40){
        sum = sum % 40;
        if(sum == 12){
            printf ("28\n");
        } else if(sum == 35){
            printf ("7\n");
        } else{
            printf ("%d\n", sum);
        }
    } else if(sum < 40){
        if(sum == 12){
            printf ("28\n");
        } else if(sum == 35){
            printf ("7\n");
        } else{
            printf ("%d\n", sum);
        }
    }
    return 0;
}

还要澄清一下，我仍然是编程的初学者(就像参加C.SCi课程只有两个月的时间一样)，因此，如果您能像我这样解释我不是一个很好的专家，就可以对我进行解释. /p>

Also just to clarify, that I'm still a beginner in programming (like only 2 months into C.SCi course), so if you could explain it to me like I'm not a expert that would be great.

推荐答案

scanf没有执行所需功能的功能.您可以只使用if来验证输入.

scanf has no functionality to do what you want. You can just use an if to validate input.

if(scanf("%d", &diceResult) != 1 || diceResult < 2 || diceResult > 12) {
//handle invalid input here
}

如果输入无效，则取决于您要执行的操作.您可以忽略输入并要求用户输入有效的数字，可以退出整个程序或忽略错误，或者完全忽略其他内容.

If the input is invalid it is up to you what you want to do. You could ignore the input and ask the user to enter a valid number, you can quit the whole program or just ignore the error, or something else entirely.

您也可以使用while反复检查输入:

You can also check the input repeatedly with an while:

while(scanf("%d", &diceResult) != 1 || diceResult < 2 || diceResult > 12) {
//prompt user to enter valid input here
}

正如chux所提到的，处理无效输入的一部分是假定无效输入并检查EOF.

As mentioned by chux, part of handling invalid input would be to cosume the invalid input and check for EOF.

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scanf("%d", &diceResult) != 1将确保scanf实际上只读取一个数字，并且不会发生解析错误.

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The scanf("%d", &diceResult) != 1 will assure, that scanf actually read exactly one number and no parsing errors occurred.

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