实验6 仿写Linux下的ls-l命令C++实现

实现类似于Linux下的ls -l命令可以使用C++的文件操作库和标准库函数实现。具体步骤如下：

1. 包含头文件

#include <iostream>
#include <fstream>
#include <dirent.h>
#include <sys/stat.h>
#include <pwd.h>
#include <grp.h>
#include <time.h>

2. 定义函数

void listDir(const char* path);
void printStat(struct stat st);
void printFileType(mode_t mode);
void printPermissions(mode_t mode);
void printTime(time_t t);

3. 实现函数

void listDir(const char* path)
{
    DIR* dir = opendir(path);
    if (dir == NULL)
    {
        std::cerr << "Failed to open directory " << path << std::endl;
        return;
    }

    dirent* entry;
    while ((entry = readdir(dir)) != NULL)
    {
        std::string filename(entry->d_name);
        if (filename == "." || filename == "..")
        {
            continue;
        }

        std::string filepath(path);
        filepath += "/";
        filepath += filename;

        struct stat st;
        if (stat(filepath.c_str(), &st) != 0)
        {
            std::cerr << "Failed to get file stat: " << filepath << std::endl;
            continue;
        }

        printStat(st);
        std::cout << " " << filename << std::endl;
    }

    closedir(dir);
}

void printStat(struct stat st)
{
    printFileType(st.st_mode);
    printPermissions(st.st_mode);
    std::cout << " " << st.st_nlink << " ";

    struct passwd* pw = getpwuid(st.st_uid);
    if (pw == NULL)
    {
        std::cerr << "Failed to get user name" << std::endl;
        return;
    }
    std::cout << pw->pw_name << " ";

    struct group* gr = getgrgid(st.st_gid);
    if (gr == NULL)
    {
        std::cerr << "Failed to get group name" << std::endl;
        return;
    }
    std::cout << gr->gr_name << " ";

    std::cout << st.st_size << " ";
    printTime(st.st_mtime);
}

void printFileType(mode_t mode)
{
    if (S_ISREG(mode))
    {
        std::cout << "-";
    }
    else if (S_ISDIR(mode))
    {
        std::cout << "d";
    }
    else if (S_ISCHR(mode))
    {
        std::cout << "c";
    }
    else if (S_ISBLK(mode))
    {
        std::cout << "b";
    }
    else if (S_ISFIFO(mode))
    {
        std::cout << "p";
    }
    else if (S_ISLNK(mode))
    {
        std::cout << "l";
    }
    else if (S_ISSOCK(mode))
    {
        std::cout << "s";
    }
}

void printPermissions(mode_t mode)
{
    std::cout << ((mode & S_IRUSR) ? "r" : "-");
    std::cout << ((mode & S_IWUSR) ? "w" : "-");
    std::cout << ((mode & S_IXUSR) ? "x" : "-");
    std::cout << ((mode & S_IRGRP) ? "r" : "-");
    std::cout << ((mode & S_IWGRP) ? "w" : "-");
    std::cout << ((mode & S_IXGRP) ? "x" : "-");
    std::cout << ((mode & S_IROTH) ? "r" : "-");
    std::cout << ((mode & S_IWOTH) ? "w" : "-");
    std::cout << ((mode & S_IXOTH) ? "x" : "-");
}

void printTime(time_t t)
{
    struct tm* tm = localtime(&t);
    char str[100];
    strftime(str, sizeof(str), "%Y-%m-%d %H:%M:%S", tm);
    std::cout << str;
}

4. 测试

int main()
{
    listDir(".");
    return 0;
}

这样就可以实现类似于Linux下的ls -l命令。