C++如何分割大文本文件以进行多线程读取

#include <iostream>
#include <fstream>
#include <thread>
#include <vector>
#include <string>

void processFileBlock(const std::string& filename, std::streampos start, std::streampos blockSize) {
    std::ifstream file(filename);
    if (file) {
        // 定位到当前线程应该读取的起始位置
        file.seekg(start);

        // 读取文件块
        std::string data;
        data.resize(blockSize);
        file.read(&data[0], blockSize);

        // 处理文件块
        // ...

        // 输出结果
        std::cout << "Processed file block: " << data << std::endl;
    }
}

int main() {
    const std::string filename = "large_text_file.txt";
    const int numThreads = 4;

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

        // 计算每个线程应该读取的文件块大小
        std::streampos blockSize = fileSize / numThreads;

        // 创建线程并分配任务
        std::vector<std::thread> threads;
        for (int i = 0; i < numThreads; ++i) {
            std::streampos start = i * blockSize;
            threads.emplace_back(processFileBlock, filename, start, blockSize);
        }

        // 等待所有线程完成
        for (auto& thread : threads) {
            thread.join();
        }
    }

    return 0;
}