How to read from env in Windows in c++

Question

I want to get system folder in windows, by reading SystemRoot. How can I do it? many thanks!

Answer 1

If you want to read the environment variables, use getenv or GetEnvironmentVariable .

However, if you want to find the %SYSTEMROOT% directory consider using GetWindowsFolder

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For other special folders, you can use SHGetKnownFolderPath or SHGetFolderPath

Answer 2

There's a windows API you should use instead: GetWindowsDirectory

But if you do want to read from the environment you can use GetEnvironmentVariable , or from the C runtime with getenv or even get the environment pointer from the unofficial third main argument int main(argc, argv, envp) which is supported by the VC runtime.

Answer 3

This should be fairly easy with GetEnvironmentVariable():

DWORD WINAPI GetEnvironmentVariable(
  __in_opt   LPCTSTR lpName,
  __out_opt  LPTSTR lpBuffer,
  __in       DWORD nSize
);

See MSDN on GetEnvironmentVariable() for more infos and some examples (the function is used in Example 2)