用C++读取12-15GB ASCII文件的最佳方法

#include <fstream>
#include <iostream>

int main() {
    std::ifstream file("filename.txt");
    if (file.is_open()) {
        std::string line;
        while (std::getline(file, line)) {
            // 处理每一行数据
        }
        file.close();
    } else {
        std::cout << "无法打开文件" << std::endl;
    }
    return 0;
}

#include <fstream>
#include <iostream>

int main() {
    std::ifstream file("filename.txt");
    if (file.is_open()) {
        // 设置缓冲区大小为1MB
        const int bufferSize = 1024 * 1024;
        char* buffer = new char[bufferSize];
        file.rdbuf()->pubsetbuf(buffer, bufferSize);

        std::string line;
        while (std::getline(file, line)) {
            // 处理每一行数据
        }
        file.close();
        delete[] buffer;
    } else {
        std::cout << "无法打开文件" << std::endl;
    }
    return 0;
}

#include <fstream>
#include <iostream>

int main() {
    std::ifstream file("filename.txt");
    if (file.is_open()) {
        const int blockSize = 1024 * 1024; // 每次读取1MB
        char* buffer = new char[blockSize];

        // 获取文件大小
        file.seekg(0, std::ios::end);
        std::streampos fileSize = file.tellg();
        file.seekg(0, std::ios::beg);

        // 分块读取文件
        for (std::streampos pos = 0; pos < fileSize; pos += blockSize) {
            file.read(buffer, blockSize);
            std::streamsize bytesRead = file.gcount();
            // 处理读取的数据块
        }

        file.close();
        delete[] buffer;
    } else {
        std::cout << "无法打开文件" << std::endl;
    }
    return 0;
}