Detailed explanation of file flow operations in C + +

In C + + programming, file stream operation is an important means of processing file input and output.

This article will detail how to use ifstreamSumofstreamThe class performs file read and write operations, including the processing of text files and binary files, and comes with exception handling code.

1. File flow basics.

In C + +, file streams are divided into input file streams ( ifstream) and output file stream ( ofstream）。

ifstreamUsed to read data from files, while ofstreamUsed to write data to a file.

\n#

Contains header files.

First, we need to include the necessary header files:

#include 
#include 
#include 

2. Use ofstreamWrite to file.

\n#

Write a text file.

Below is an example showing how to use ofstreamWrite text file:

void writeTextFile(const std::string& filename) {
    std::ofstream outFile;
    outFile.open(filename); // 打开文件

    if (!outFile) { // 检查文件是否成功打开
        std::cerr << "无法打开文件: " << filename << std::endl;
        return;
    }

    outFile << "Hello, World!" << std::endl; // 写入文本内容
    outFile << "This is a text file." << std::endl;

    outFile.close(); // 关闭文件
}

\n#

Write a binary file.

For binary files, you can use writeMethod:

struct Data {
    int id;
    char name[50];
};

void writeBinaryFile(const std::string& filename) {
    std::ofstream outFile;
    outFile.open(filename, std::ios::binary); // 以二进制模式打开文件

    if (!outFile) { // 检查文件是否成功打开
        std::cerr << "无法打开文件: " << filename << std::endl;
        return;
    }

    Data data = {1, "Sample"};
    outFile.write(reinterpret_cast(&data), sizeof(data)); // 写入二进制数据

    outFile.close(); // 关闭文件
}

3. Use ifstreamRead the file.

\n#

Read text files.

Below is an example showing how to use ifstreamRead text file:

void readTextFile(const std::string& filename) {
    std::ifstream inFile;
    inFile.open(filename); // 打开文件

    if (!inFile) { // 检查文件是否成功打开
        std::cerr << "无法打开文件: " << filename << std::endl;
        return;
    }

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

    inFile.close(); // 关闭文件
}

\n#

Read the binary file.

For binary files, you can use readMethod:

void readBinaryFile(const std::string& filename) {
    std::ifstream inFile;
    inFile.open(filename, std::ios::binary); // 以二进制模式打开文件

    if (!inFile) { // 检查文件是否成功打开
        std::cerr << "无法打开文件: " << filename << std::endl;
        return;
    }

    Data data;
    inFile.read(reinterpret_cast(&data), sizeof(data)); // 读取二进制数据

    std::cout << "ID: " << data.id << ", Name: " << data.name << std::endl;

    inFile.close(); // 关闭文件
}

4. Exception handling.

When performing file operations, various abnormal situations may be encountered, such as non-existence of files, insufficient permissions, etc.

In order to improve the robustness of the program, we can use exception handling mechanism to catch and handle these exceptions.

\n#

Use the try-catch block for exception handling.

The following is how to use it in file operations try-catchExamples of block exception handling:

void safeWriteTextFile(const std::string& filename) {
    try {
        std::ofstream outFile;
        outFile.open(filename); // 打开文件

        if (!outFile) { // 检查文件是否成功打开
            throw std::ios_base::failure("无法打开文件: " + filename);
        }

        outFile << "Hello, World!" << std::endl; // 写入文本内容
        outFile << "This is a text file." << std::endl;

        outFile.close(); // 关闭文件
    } catch (const std::ios_base::failure& e) { // 捕获文件操作异常
        std::cerr << "文件操作失败: " << e.what() << std::endl;
    }
}

Similarly, we can add exception handling for read operations:

void safeReadTextFile(const std::string& filename) {
    try {
        std::ifstream inFile;
        inFile.open(filename); // 打开文件

        if (!inFile) { // 检查文件是否成功打开
            throw std::ios_base::failure("无法打开文件: " + filename);
        }

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

        inFile.close(); // 关闭文件
    } catch (const std::ios_base::failure& e) { // 捕获文件操作异常
        std::cerr << "文件操作失败: " << e.what() << std::endl;
    }
}

5. Precautions in practical applications.

In actual development, we need to pay attention to the following points: 1. # Path problem #: Make sure the file path provided is correct, especially when developing across platforms.

2. # Permission Issue #: Ensure that the program has sufficient permissions to access and modify the target file.

3. # Resource Management #: Close files in time to avoid resource leakage.

You can use RAII (Resource Acquisition Is Initialization) technology to automatically manage resources through smart pointers or object destructors.

4. # Error Handling #: Always perform error checking and exception handling to improve program robustness and user experience.

6. Summary.

This article details how to use it in C + + ifstreamSumofstreamThe class performs file read and write operations, including the processing of text files and binary files, and comes with exception handling code.

By mastering these basic skills, you can efficiently operate files in actual projects and improve the stability and reliability of the program.

Hope this article helps you!