C++17 什么新：错误 C4996：'getenv'：此 function 或变量可能不安全。 考虑改用 _dupenv_s

Question

i try to do a simple task and get environment variable both in Linux and windows all docs point to use: std::getenv but when i run the compilation in windows 10 using visual studio 2019 I'm getting:

error C4996: 'getenv': This function or variable may be unsafe. Consider using _dupenv_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS

This is the function:

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

i found only this thread , which i don't understand what is the solution for cross-platform solution.

Answer 1

The compiler message says it all:

error C4996: 'getenv': This function or variable may be unsafe. Consider using _dupenv_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS

The warnings is MSVC specific. It warns about usage of an unsafe C standard function.

If you only need to compile on MSVC, then

Consider using _dupenv_s instead.

If you need cross platform compatibility, then

To disable deprecation, use _CRT_SECURE_NO_WARNINGS

Which is a define, so just #define _CRT_SECURE_NO_WARNINGS . Another solution would be to disable the warning ( #pragma warning(disable: 4996) ).

See also Remove secure warnings (_CRT_SECURE_NO_WARNINGS) from projects by default in Visual Studio .