如何在C++中对文件进行大std::vector<std::vector<float>>读写

#include <iostream>
#include <fstream>
#include <vector>

std::vector<std::vector<float>> readFile(const std::string& filename) {
    std::vector<std::vector<float>> data;
    std::ifstream file(filename);
    if (file.is_open()) {
        std::string line;
        while (std::getline(file, line)) {
            std::vector<float> row;
            std::istringstream iss(line);
            float value;
            while (iss >> value) {
                row.push_back(value);
            }
            data.push_back(row);
        }
        file.close();
    }
    return data;
}

std::vector<std::vector<float>> data = readFile("filename.txt");

void writeFile(const std::string& filename, const std::vector<std::vector<float>>& data) {
    std::ofstream file(filename);
    if (file.is_open()) {
        for (const auto& row : data) {
            for (const auto& value : row) {
                file << value << " ";
            }
            file << std::endl;
        }
        file.close();
    }
}

writeFile("filename.txt", data);