关于头文件

用gcc编译一个程序，程序包含了“ourhdr.h”，但出现错误提示，没有这个头文件

#include <sys/types.h>
#include <dirent.h>
#include <ourhdr.h>

int main(int argc,char *argv[])
{
    DIR             *dp;
    struct dirent   *dirp;
    if (argc !=2)
        err_quit("a single argument (the dirname) is required");
    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);
}

编译的结果提示如下：list_allfile.c:3:60: ourhdr.h: 没有那个文件或目录
list_allfile.c: In function `main':
list_allfile.c:10: `NULL' undeclared (first use in this function)
list_allfile.c:10: (Each undeclared identifier is reported only once
list_allfile.c:10: for each function it appears in.)
有朋友告诉我这个头文件是APUE里边的头文件

应该怎么重新改写并编译一下呢？