C++ 实现ls命令
```
#include <iostream>
#include <algorithm>
#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <sys/types.h>
#include <string.h>
#include <string>
#include <sys/stat.h>
#include <unistd.h>
#include <pwd.h>//下边两个是为了显示用户名与组名
#include <grp.h>
#include <sys/time.h>
using namespace std;
bool cmp( string s1,string s2){
return s1<s2;
}
string fileType(char *fileName){
struct stat buf;
struct passwd *pw;
struct group *gr;
char s[100];
struct tm *ttime;
pw = getpwuid(getuid());
gr = getgrgid(buf.st_gid);
string type="";
stat(fileName, &buf);
switch(buf.st_mode & S_IFMT) //获取字符串的属性：普通文件-、目录d、字符设备c、块设备b、管道文件p、连接文件l、套接字文件s
{
case S_IFREG://普通文件
type="-";
break;
case S_IFDIR:
type="d";
break;
case S_IFCHR://字符装置
type="c";
break;
case S_IFBLK://区块装置
type="b";
break;
case S_IFIFO://先进先出
type="p";
break;
case S_IFLNK://符号链接
type="l";
break;
case S_IFSOCK://socket
type="s";
break;
}
switch(buf.st_mode & S_IRWXU)//当前用户
{
case 448:
type+="rwx";
break;
case 384:
type+="rw-";
break;
case 320:
type+="r-x";
break;
case 192:
type+="-wx";
break;
case 256:
type+="r--";
break;
case 128:
type+="-w-";
break;
case 64:
type+="--x";
break;
}
switch(buf.st_mode & S_IRWXG)//组用户权限
{
case 56:
type+="rwx";
break;
case 48:
type+="rw-";
break;
case 40:
type+="r-x";
break;
case 24:
type+="-wx";
break;
case 32:
type+="r--";
break;
case 16:
type+="-w-";
break;
case 8:
type+="--x";
break;
}
switch(buf.st_mode & S_IRWXO)//其他用户权限
{
case 7:
type+="rwx";
break;
case 6:
type+="rw-";
break;
case 5:
type+="r-x";
break;
case 3:
type+="-wx";
break;
case 4:
type+="r--";
break;
case 2:
type+="-w-";
break;
case 1:
type+="--x";
break;
}
ttime = localtime(&(buf.st_mtime));
strftime(s,sizeof(s),"%Y-%m-%d %H:%M:%S",ttime);
type+=to_string(buf.st_nlink);
type+=" ";
string n=pw->pw_name;
type+=n;
type+=" ";
type+=gr->gr_name;
type+=" ";
type+=to_string(buf.st_size);
type+=" ";
type+=s;
return type;
}
int main()
{
DIR *dir;
char s[100];
string data[100];
int tot=0;
struct dirent *rent;
dir =opendir(".");
while(rent=readdir(dir))
{
strcpy(s,rent->d_name);
if(s[0]!='.'){
data[tot]=s;
tot++;
}
}
sort(data,data+tot,cmp);
for(int i=0;i<tot;i++){
char * fileName=(char*)data[i].data();
cout<<fileType(fileName)<<" "<<data[i]<<endl;
}
closedir(dir);
return 0;
}
```
