如何在 C 中对 argv 的元素进行排序? [英] How do I sort the elements of argv in C?

问题描述

我正在尝试按字母顺序对 argv 的元素进行排序.

I am trying to alphabetically sort the elements of argv.

以下代码行给我带来了问题:

The following line of code is giving me problems:

qsort(argv[optind], argc - optind, sizeof(argv[optind]), sort);

具体来说，最后一个参数给我带来了麻烦，比较函数，下面给出:

Specifically, the last argument is giving me trouble, the comparison function, which is given below:

int
sort(const void *a, const void * b)
{    
    return(strcmp( (char*)a, (char*)b ));
}

目前，它编译得很好，但是当我运行它时，我最终遇到了分段错误.

At the moment, it compiles fine, but I end up getting a segmentation fault when I run it.

推荐答案

qsort(3) 的手册页包含一个示例，它完全符合您的要求.它还解释了原因:

The man page for qsort(3) contains one example, which does exactly what you want. It also explains why:

http://linux.die.net/man/3/qsort

总结:您在 qsort() 第一个参数上缺少一级引用，并且在 sort() 函数内部缺少一级取消引用.

Summary: You are missing one level of referencing on the qsort() first argument, and missing one level of dereferencing inside the sort() function.

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