如何将向量值写入文件 [英] How to write vector values to a file

问题描述

我的向量很大。

我使用的方式极大地增加了程序的运行时间。首先是将所有值写入使用 stringstreams 计算的字符串，然后将字符串写入文件。另一种方法是在事实之后制作一个长字符串并将其写入文件。但是，这两者都很慢。

The ways that I use multiply the run-time of the program hugely. The first is write all values to a string as they are calculated using stringstreams and later write the string to a file. The other method is to make a long string after the fact and write that to the file. However, both of these are very slow.

有没有一种方法可以立即将换行符的矢量立即插入换行符中？

Is there a way to just write the vector's values to the text file immediately with line breaks?

推荐答案

使用 std :: ofstream ， std :: ostream_iterator 和 std :: copy（） 是执行此操作的常用方法。这是 std :: string 使用C ++ 98语法（此问题在C ++ 11之前问）：

Using std::ofstream, std::ostream_iterator and std::copy() is the usual way to do this. Here is an example with std::strings using C++98 syntax (the question was asked pre-C++11):

#include <fstream>
#include <iterator>
#include <string>
#include <vector>

int main()
{
    std::vector<std::string> example;
    example.push_back("this");
    example.push_back("is");
    example.push_back("a");
    example.push_back("test");

    std::ofstream output_file("./example.txt");
    std::ostream_iterator<std::string> output_iterator(output_file, "\n");
    std::copy(example.begin(), example.end(), output_iterator);
}

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