程序1-1 列出目录中文件

#include "apue.h"
#include <dirent.h>

int main(int argc, char* argv[])
{
    DIR* dp;
    struct dirent* dirp;

    if (argc != 2)
        err_quit("usage: ls directory_name");

    if ((dp = opendir(argv[1])) == NULL)
    {
        err_sys("can‘t open %s", argv[1]);
    }
    while ((dirp = readdir(dp)) != NULL)
    {
        printf("%s\n", dirp->d_name);
    }

    closedir(dp);
    exit(0);
}