向后读取文件？ [英] Read a file backwards?

问题描述

有没有办法逐行读取文件，而不必从头开始读取文件，开始向后读？

Is there a way to read a file backwards, line by line, without having to go through the file from the beginning to start reading backwards?

推荐答案

根据注释，一个可能的（非常简单）的替代方法将读取行到向量。例如：

As per comment, a possible (quite simple) alternative would be read the lines into a vector. For example:

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

int main()
{
    std::ifstream in("main.cpp");

    if (in.is_open())
    {
        std::vector<std::string> lines_in_reverse;
        std::string line;
        while (std::getline(in, line))
        {
            // Store the lines in reverse order.
            lines_in_reverse.insert(lines_in_reverse.begin(), line);
        }
    }
}

编辑：

根据 jrok 和 Loki Astari 的评论， push_back（）会更有效率，但行将在文件顺序，因此反向迭代（ reverse_iterator ）或 std :: reverse（） ：

As per jrok's and Loki Astari's comments, push_back() would be more efficient but the lines would be in file order, so reverse iteration (reverse_iterator) or std::reverse() would be necessary:

    std::vector<std::string> lines_in_order;
    std::string line;
    while (std::getline(in, line))
    {
        lines_in_order.push_back(line);
    }

这篇关于向后读取文件？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！