如何在 C++ 中读取 Linux 环境变量 [英] How to read Linux environment variables in c++
问题描述
在我的 c++ 程序中,我想将一些环境变量从 shell 加载到一些字符串中.如何做到这一点?
In my c++ program I want to load some environment variables from the shell into some strings. How can this be done?
推荐答案
使用 getenv() 函数 - 见 http://en.cppreference.com/w/cpp/utility/program/getenv.我喜欢这样包装:
Use the getenv() function - see http://en.cppreference.com/w/cpp/utility/program/getenv. I like to wrap this as follows:
std::string GetEnv( const std::string & var ) {
const char * val = std::getenv( var.c_str() );
if ( val == nullptr ) { // invalid to assign nullptr to std::string
return "";
}
else {
return val;
}
}
这避免了环境变量不存在时的问题,并允许我轻松使用C++字符串来查询环境.当然,它不允许我测试环境变量是否不存在,但总的来说这在我的代码中不是问题.
which avoids problems when the environment variable does not exist, and allows me to use C++ strings easily to query the environment. Of course, it does not allow me to test if an environment variable does not exist, but in general that is not a problem in my code.
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