在C ++中访问环境变量

问题描述

我想要访问我正在编写的C ++程序中的 $ HOME 环境变量。如果我在C中编写代码，我只需使用 getenv（）函数，但是我想知道是否有更好的方法来实现。这是我迄今为止的代码：

I'd like to have access to the $HOME environment variable in a C++ program that I'm writing. If I were writing code in C, I'd just use the getenv() function, but I was wondering if there was a better way to do it. Here's the code that I have so far:

std::string get_env_var( std::string const & key ) {
    char * val;
    val = getenv( key.c_str() );
    std::string retval = "";
    if (val != NULL) {
        retval = val;
    }
    return retval;
}

我应该使用 getenv（）访问C ++中的环境变量？有没有什么问题，我有可能遇到这种情况，我可以避免一点点的知识？

Should I use getenv() to access environment variables in C++? Are there any problems that I'm likely to run into that I can avoid with a little bit of knowledge?

推荐答案

有在C ++中使用 getenv（）没有任何问题。它由 stdlib.h 定义，或者如果您更喜欢标准库实现，则可以包括 cstdlib 并访问函数通过 std :: 命名空间（即 std :: getenv（））。这绝对没有错。实际上，如果你关心可移植性，这两个版本中的任何一个都是首选的。

There is nothing wrong with using getenv() in C++. It is defined by stdlib.h, or if you prefer the standard library implementation, you can include cstdlib and access the function via the std:: namespace (i.e., std::getenv()). Absolutely nothing wrong with this. In fact, if you are concerned about portability, either of these two versions is preferred.

如果你不是关心可移植性，你是使用托管C ++，您可以使用.NET等效的 - 。如果你想要Windows的非.NET等价物，你可以使用 Win32功能。

If you are not concerned about portability and you are using managed C++, you can use the .NET equivalent - System::Environment::GetEnvironmentVariable(). If you want the non-.NET equivalent for Windows, you can simply use the GetEnvironmentVariable() Win32 function.

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