How to close a file using C++?

There are two ways to close a C++ file: using the fclose() function (applicable to C stream files) and using the close() member function of the ifstream and ofstream classes (applicable to C++ standard library file streams). These methods ensure that the file is closed before the program ends to avoid resource leaks, and the close() member function can automatically close the file, while fclose() requires an explicit call.

How to close a file using C++

File manipulation is a common task in programming. In C++, there are several ways to close a file. This article will detail the method of closing C++ files and provide a practical case to demonstrate how to use it.

Method 1: Use the fclose() function

fclose() is a standard C function used to close a file. It accepts a FILE* type pointer as parameter, pointing to the file to be closed. The syntax is as follows:

int fclose(FILE *stream);

Method 2: Use the close() member function of the ifstream and ofstream classes

ifstream and # in the C++ standard library The ##ofstream class provides the close() member function for closing the file. The syntax is as follows:

void close();

Practical case

The following code example demonstrates how to use the

fclose() function to close a file:

#include <stdio.h>

int main() {
  // 打开一个文件
  FILE *file = fopen("test.txt", "w");

  // ... 在文件中写入数据 ...

  // 关闭文件
  int result = fclose(file);

  // 检查是否关闭成功
  if (result != 0) {
    printf("无法关闭文件！\n");
    return 1;
  }

  printf("文件已成功关闭。\n");
  return 0;
}

The following code example demonstrates how to use the

close() member function of the ifstream class to close a file:

#include <iostream>
#include <fstream>

int main() {
  // 打开一个文件
  std::ifstream file("test.txt");

  // ... 从文件中读取数据 ...

  // 关闭文件
  file.close();

  // 检查是否关闭成功
  if (!file.is_open()) {
    std::cout << "文件已成功关闭。" << std::endl;
  } else {
    std::cout << "无法关闭文件！" << std::endl;
  }
  
  return 0;
}

Note:

Make sure to close all files before the program ends to avoid resource leaks.
• For C stream files, please use the
• fclose() function to explicitly close.
For
• ifstream and ofstream objects, automatic closing can be done using the destructor, but explicit closing ensures that the file is closed as quickly as possible.

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