如何从fgets检测空字符串 [英] How to detect empty string from fgets

问题描述

我试图将来自stdin的fgets输入检测为空(当我按Enter而不输入任何内容时).这是我的程序:

I'm trying to detect the input of fgets from stdin as empty (when I press enter without entering in anything). Here is my program:

int main()
{
    char input[1000];
    printf("Enter :");
    fgets(input, 1000, stdin);
    input[strlen(input) - 1] = '\0';

    if(input != '\0'){
        printf("hi");
    }

    return 0;

}

我想执行某种条件，使其不打印任何内容，但显然这种方式是不正确的.我还尝试了NULL，该方法无效.

I want to do some sort of condition which makes it not print anything, but clearly this way isn't right. I also tried NULL, which did not work.

谢谢！

推荐答案

我认为这是最易读的(但性能不佳):

I think this is the most readable (but not performant):

if (strlen(input) != 0) {
    printf("hi");
}

但是为了教学，这里是您的风格，但随后进行了修正:

But for the sake of teaching here is your style, but then fixed:

if (input[0] != '\0') {
    printf("hi");
}

为什么input[0]?因为input像这样对数组的第一个元素进行操作，就像指针一样，因此必须首先取消引用它才能使比较有用.

Why input[0]? Because input acts like a pointer to the first element of the array if you compare it like that and you first have to dereference it to make the comparison useful.

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