什么是最优雅的方式用c ++读取文本文件？ [英] What is the most elegant way to read a text file with c++?

问题描述

我想用c ++读取一个文本文件的全部内容到一个 std :: string 对象。

使用Python，我可以写：

  text = open text.txt，rt）。read（）
  

我讨厌丑陋的东西，所以我想知道 - 什么是最优雅的方式用C ++阅读文本文件？
感谢。

解决方案

有很多方法，你选择哪一个是最优雅的。

读取到字符*：

  ifstream文件（file.txt，ios :: in | ios :: binary | ios :: ate）; 
 if（file.is_open（））
 {
 file.seekg（0，ios :: end）; 
 size = file.tellg（）; 
 char * contents = new char [size]; 
 file.seekg（0，ios :: beg）; 
 file.read（contents，size）; 
 file.close（）; 
 // ...做一些事情
 delete [] content; 
} 
  

into std :: string：

  std :: ifstream in（file.txt）; 
 std :: string contents（（std :: istreambuf_iterator< char>（in）），
 std :: istreambuf_iterator< char>（））; 
  

进入向量< char>：

  std :: ifstream in（file.txt）; 
 std :: vector< char> contents（（std :: istreambuf_iterator< char>（in）），
 std :: istreambuf_iterator< char>（））; 
  

使用stringstream转换为字符串：

  std :: ifstream in（file.txt）; 
 std :: stringstream buffer; 
 buffer<< in.rdbuf（）; 
 std :: string contents（buffer.str（））; 
  

file.txt只是一个例子，一切都适用于二进制文件，在ifstream构造函数中使用ios :: binary。

I'd like to read whole content of a text file to a std::string object with c++.

With Python, I can write:

text = open("text.txt", "rt").read()

It is very simple and elegant. I hate ugly stuff, so I'd like to know - what is the most elegant way to read a text file with C++? Thanks.

解决方案

There are many ways, you pick which is the most elegant for you.

Reading into char*:

ifstream file ("file.txt", ios::in|ios::binary|ios::ate);
if (file.is_open())
{
    file.seekg(0, ios::end);
    size = file.tellg();
    char *contents = new char [size];
    file.seekg (0, ios::beg);
    file.read (contents, size);
    file.close();
    //... do something with it
    delete [] contents;
}

Into std::string:

std::ifstream in("file.txt");
std::string contents((std::istreambuf_iterator<char>(in)), 
    std::istreambuf_iterator<char>());

Into vector<char>:

std::ifstream in("file.txt");
std::vector<char> contents((std::istreambuf_iterator<char>(in)),
    std::istreambuf_iterator<char>());

Into string, using stringstream:

std::ifstream in("file.txt");
std::stringstream buffer;
buffer << in.rdbuf();
std::string contents(buffer.str());

file.txt is just an example, everything works fine for binary files as well, just make sure you use ios::binary in ifstream constructor.

这篇关于什么是最优雅的方式用c ++读取文本文件？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！