警告：指针和整数之间的比较在C [默认启用] [英] warning: comparison between pointer and integer [enabled by default] in c

问题描述

我要检查用户输入是否仅包含数字或没有。所以，我用下面的code：

I want to check whether the user input contains only digits or not. So, I use the following code:

for(i = 0; argv[1][i] != NULL; i++)
    if(!isdigit(argv[1][i]))
    {
        printf("Error");
        return -1;
    }

它运作良好，但我得到了这样的警告：

It works well but I got this warning:

warning: comparison between pointer and integer [enabled by default]

因为的argv [1] [I] 是一个整数， NULL 是一个指针。我怎样才能避免这样的警告？

since argv[1][i] is an Integer and NULL is a pointer. How can I avoid such warning?

推荐答案

NULL 是不一样的空终止符。您应该使用'\\ 0'代替。

NULL is not the same as the null-terminator character. You should use '\0' instead.

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