C++17 Filesystem 实用教程

#include <filesystem>
#include <iostream>

namespace fs = std::filesystem;

int main() {
  fs::path filePath = "example.txt";
  if (fs::exists(filePath)) {
    std::cout << "文件存在!\n";
  } else {
    std::cout << "文件不存在.\n";
  }
  return 0;
}

fs::path dirPath = "new_directory";
fs::create_directory(dirPath);  // 创建单个目录
fs::remove(dirPath);            // 删除目录

fs::path dirPath = "."; // 当前目录
for (const auto& entry : fs::recursive_directory_iterator(dirPath)) {
    std::cout << entry.path() << std::endl;
}

fs::path filePath = "example.txt";
if (fs::exists(filePath)) {
  std::cout << "文件大小: " << fs::file_size(filePath) << " 字节\n";
  std::cout << "是否为正解文件: " << fs::is_regular_file(filePath) << "\n";
  std::cout << "文件最后修改时间: "
            << fs::last_write_time(filePath).time_since_epoch().count()
            << "\n";
}

fs::copy("source.txt", "destination.txt", fs::copy_options::overwrite_existing); // 复制文件
fs::rename("old_name.txt", "new_name.txt"); // 重命名文件

fs::path symlinkPath = "symbolic_link";
fs::path targetPath = "target_file";
fs::create_symlink(targetPath, symlinkPath);  // 创建符号链接
if (fs::is_symlink(symlinkPath)) {
  std::cout << symlinkPath << " 是符号链接, 指向 "
            << fs::read_symlink(symlinkPath) << std::endl;
}

// 1. 路径组合
fs::path base = "/home/user/documents";
fs::path file = "report.pdf";
fs::path fullPath = base / file;  // 使用 / 操作符组合路径
std::cout << "组合路径: " << fullPath << std::endl;

fs::path filepath = "/home/user/documents/report.pdf";
std::cout << "文件名: " << filepath.filename() << std::endl;
std::cout << "主文件名: " << filepath.stem() << std::endl;
std::cout << "扩展名: " << filepath.extension() << std::endl;
std::cout << "父路径: " << filepath.parent_path() << std::endl;

fs::path p1 = "/home/user/documents";
fs::path p2 = "/home/user/pictures";
fs::path rel = fs::relative(p2, p1);  // 计算从 p1 到 p2 的相对路径
std::cout << "相对路径: " << rel << std::endl;  // ../pictures

fs::path complex = "/home/user/documents/work/report.pdf";
std::cout << "路径分解:" << std::endl;
for (const auto& part : complex) {
  std::cout << "  " << part << std::endl;
}

fs::path messy = "home/user/../user/./documents/report.pdf";
std::cout << "规范化路径: " << messy.lexically_normal() << std::endl;

// 使用 std::filesystem::equivalent 检查两个路径是否指向同一文件
fs::path linkPath =
    "link_to_report.pdf";  // 假设这是一个指向 report.pdf 的符号链接
fs::path actualPath = "documents/report.pdf";
try {
  if (fs::equivalent(linkPath, actualPath)) {
    std::cout << "路径 " << linkPath << " 和 " << actualPath
              << " 指向同一文件." << std::endl;
  } else {
    std::cout << "路径 " << linkPath << " 和 " << actualPath
              << " 不指向同一文件." << std::endl;
  }
} catch (const fs::filesystem_error& e) {
  std::cerr << "文件系统错误: " << e.what() << std::endl;
}

fs::path prefix = "backup_";
fs::path filename = "report.pdf";
fs::path newPath = prefix.string() + filename.string();
std::cout << "拼接路径: " << newPath << std::endl;

fs::path checkPath = "/home/user/documents/report.pdf";
std::cout << "是否为绝对路径: " << checkPath.is_absolute() << std::endl;
std::cout << "是否有扩展名: " << checkPath.has_extension() << std::endl;
std::cout << "是否有文件名: " << checkPath.has_filename() << std::endl;
std::cout << "是否有父路径: " << checkPath.has_parent_path() << std::endl;

fs::path modPath = "/home/user/documents/report.pdf";
modPath.replace_filename("newreport.doc");
std::cout << "替换文件名后: " << modPath << std::endl;
modPath.replace_extension(".txt");
std::cout << "替换扩展名后: " << modPath << std::endl;