How to get file size using C++?

Question: How to get file size in C++? Answer: 1. Use the std::ifstream::tellg() member function to get the number of bytes read or written since opening the file stream; 2. Use std::filesystem::directory_iterator to traverse the files in the directory and Use std::ifstream::tellg() to calculate the number of bytes in each file and add them up to get the total size.

#How to get file size in C++?

In C++, you can use the std::ifstream class to open and read files. This class contains std::ifstream::tellg() member function which returns the number of bytes read or written since the file stream was opened. This can be used to get the size of the file.

Code example:

#include <iostream>
#include <fstream>

int main() {
  // 打开文件
  std::ifstream file("myfile.txt");
  
  // 获取文件的大小
  file.seekg(0, std::ios::end);
  int file_size = file.tellg();
  
  // 打印文件大小
  std::cout << "The file size is: " << file_size << " bytes" << std::endl;
  
  file.close();
  return 0;
}

Practical case:

The following is a method to obtain the total size of all files in a specific directory Example:

#include <iostream>
#include <fstream>
#include <filesystem>

int main() {
  std::filesystem::path directory_path("my_directory");
  
  // 遍历目录中的文件
  int total_file_size = 0;
  for (const auto& entry : std::filesystem::directory_iterator(directory_path)) {
    if (entry.is_regular_file()) {
      // 打开文件
      std::ifstream file(entry.path());
      
      // 获取文件大小并累加到总和
      file.seekg(0, std::ios::end);
      total_file_size += file.tellg();
      
      file.close();
    }
  }
  
  // 打印总文件大小
  std::cout << "The total size of all files in the directory is: " << total_file_size << " bytes" << std::endl;
  return 0;
}

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