扫描数字 [英] Scanf for digits

问题描述

我是 C 语言的新手，我有一个关于仅用于数字的 scanf 的问题.我需要做的是输入只有 3 位数字的 scanf，其他字符或符号应该被评估为垃圾.或者我可能需要使用 isdigit() 但我不确定它是如何工作的.我就是这样，但我知道它不起作用:

I am pretty new in C and I have a question about scanf just for digits. What I need to do is scanf in input just 3 digits, antoher characters or symbols should be evaluate as trash. Or maybe I need use isdigit() but I am not sure how it works. I have just that, but I know that it doesn't work:

scanf("%d, %d, %d", &z, &x, &y);

推荐答案

您可以读取一个字符串，使用扫描集对其进行过滤并将其转换为整数.

You could read a string, use a scan set to filter it and convert it to an integer.

参见 scanf:http://www.cplusplus.com/reference/clibrary/cstdio/sscanf/

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

int main(void)
{
    char num1[256], num2[256], num3[256]; 

    scanf("%s %s %s", num1, num2, num3);
    sscanf(num1, num2, num3, "%[0-9]d %[0-9]d %[0-9]d", num1, num2, num3);

    int n1 = atoi(num1), n2 = atoi(num2), n3 = atoi(num3); // convert the strings to int

    printf("\n%d %d %d\n", n1, n2, n3);

    return 0;
}

样本输入 &输出:

Sample Input & Output:

2332jbjjjh 7ssd 100

2332 7 100

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