How to put the contents of getenv() into a string [duplicate]

问题

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Closed 9 years ago.

Possible Duplicate:
How to read Linux environment variables in c++

How can the following be changed to do what it's supposed to do?

string s = getenv("PATH");

回答1:

You have to check that the getenv succeeded first:

char const* tmp = getenv( "PATH" );
if ( tmp == NULL ) {
    //  Big problem...
} else {
    std::string s( tmp );
    //  ...
}

(Supposing I've guessed correctly with regards to "what it's supposed to do".)

回答2:

std::string getEnvVar(std::string const& key)
{
    char const* val = getenv(key.c_str()); 
    return val == NULL ? std::string() : std::string(val);
}

来源：https://stackoverflow.com/questions/5867242/how-to-put-the-contents-of-getenv-into-a-string