浅析C++中的多态与文件操作

class Animal {
public:
  virtual void makeSound() = 0; // 虚函数声明
};

class Cat : public Animal {
public:
  void makeSound() override {
    cout << "Meow!" << endl;
  }
};

class Dog : public Animal {
public:
  void makeSound() override {
    cout << "Woof!" << endl;
  }
};

class Bird : public Animal {
public:
  void makeSound() override {
    cout << "Chirp!" << endl;
  }
};

#include <iostream>
#include <fstream>

using namespace std;

int main() {
  // 创建 ofstream 对象并打开文件
  ofstream myFile("myfile.txt");

  // 检查文件是否打开成功
  if (myFile.is_open()) {
    // 将文本写入文件
    myFile << "This is a line of text in my file." << endl;

    // 关闭文件
    myFile.close();
    cout << "File written successfully." << endl;
  } else {
    cout << "Error opening file." << endl;
  }

  return 0;
}

#include <iostream>
#include <fstream>

using namespace std;

int main() {
  // 创建 ifstream 对象并打开文件
  ifstream myFile("myfile.txt");

  // 检查文件是否打开成功
  if (myFile.is_open()) {
    string line;

    // 逐行读取文件内容
    while (getline(myFile, line)) {
      cout << line << endl;
    }

    // 关闭文件
    myFile.close();
  } else {
    cout << "Error opening file." << endl;
  }

  return 0;
}

#include <iostream>
#include <filesystem>

using namespace std;
namespace fs = std::filesystem;

int main() {
  // 创建文件路径
  fs::path myFile("myfile.txt");

  // 打开文件并写入文本
  fs::ofstream ofs(myFile);
  if (ofs.is_open()) {
    ofs << "This is a line of text in my file." << endl;
    ofs.close();
  } else {
    cout << "Error opening file." << endl;
  }

  return 0;
}

#include <iostream>
#include <filesystem>

using namespace std;
namespace fs = std::filesystem;

int main() {
  // 创建文件路径
  fs::path myFile("myfile.txt");

  // 打开文件并读取内容
  fs::ifstream ifs(myFile);
  if (ifs.is_open()) {
    string line;
    while (getline(ifs, line)) {
      cout << line << endl;
    }
    ifs.close();
  } else {
    cout << "Error opening file." << endl;
  }

  return 0;
}