问题描述

我想用 C++ 将文本文件的全部内容读取到 std::string 对象.

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

使用 Python，我可以编写:

With Python, I can write:

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

它非常简单和优雅.我讨厌丑陋的东西，所以我想知道 - 用 C++ 读取文本文件的最优雅的方式是什么?谢谢.

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.

推荐答案

方法很多，你挑最适合你的.

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

读入字符*:

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;
}

进入 std::string:

Into std::string:

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

转化为向量<字符>:

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

转成字符串，使用stringstream:

Into string, using stringstream:

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

file.txt 只是一个例子，对于二进制文件一切正常，只要确保在 ifstream 构造函数中使用 ios::binary.

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

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