How to print environment value using GetEnvironmentVariable

Question

I am learning C++. I need to print the environment value of a particular environment variable. I am finding examples to check whether a environment variable is defined or not. But how to print the environment value.

GetEnvironmentVariable(_T("path"), Buffer, _MAX_PATH); returns DWORD and it is printing some integer but I need to print the exact value something like "C:\programfiles\windows".

In C# I can do this using

string abc = Environment.GetEnvironmentVariable("PATH");
cout<<a;

How to do this in VC++. Thanks

Please check `http://stackoverflow.com/questions/4130180/how-to-use-vs-c-getenvironmentvariable-as-cleanly-as-possible` — Sourav 'Abhi' Mitra, Mar 19 '14 at 07:29

Marius Bancila · Accepted Answer · 2014-03-19T13:25:50.077

1

_MAX_PATH is not probably enough to hold the whole value. You should first call the method with a nullptr and size 0 to get the size required and then allocate a buffer of that size.

auto size = GetEnvironmentVariableA("PATH", nullptr, 0);
std::string Buffer(size, 0);
GetEnvironmentVariableA("PATH", &Buffer[0], size);
std::cout << Buffer << std::endl;

UPDATE: For pre C++11 compilers:

DWORD size = GetEnvironmentVariableA("PATH", NULL, 0);

edited Mar 19 '14 at 13:25

answered Mar 19 '14 at 07:27

Marius Bancila

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I am getting error `C4430: missing type specifier - int assumed. Note: C++ does not support default-int` `error C2065: 'nullptr' : undeclared identifier` – samnaction Mar 19 '14 at 09:22
I changed it auto to int. I am using VS 2005 and not VS 2010 – samnaction Mar 19 '14 at 09:31
Should be `DWORD` actually, that's what `GetEnvironmentVariable` returns. – Marius Bancila Mar 19 '14 at 10:00
yes but what about nullptr how can I use it in VS 2005 – samnaction Mar 19 '14 at 10:09
Just replace it with `NULL` or `0`. – Marius Bancila Mar 19 '14 at 13:26

How to print environment value using GetEnvironmentVariable

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