How do I obtain an environment Variable?

have 35 years of experience. I have mostly avoided the C world. when I've had to write in it, I've done OK in VS6. VS2005 C++ is so cantankerous.

I'm writing a program that must run standalone and it must be very lean and not rely upon redistributable dlls.

I am not in need of a routine that returns the value of the %windir% environment variable in string format. My project is set for a unicode build.

The design goal is to have only the executable image and no additional dlls other than
Native XP API dlls.

char* buffer;

string x;

buffer = getenv("windir");

x = string(buffer);

will not work because it requires MSVCR80D.dll.

Thanks... Renee.

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How do I obtain an environment Variable?

J. Clark

Bugsz that did it.. thanks!

I still have tons of questions.

I have the Windir and got it thusly:

GetWindowsDirectory( infoBuf, INFO_BUFFER_SIZE );

Infobuf is defined as:

TCHAR infoBuf[INFO_BUFFER_SIZE];

Questions:

What does a TCHAR look like in memory

How do I convert from a TCHAR to a string
Mykre

The code has had that.

What I am asking is how do I convert the contents of the TCHAR to a std::string
AnwarBasha

The project is now failing when executed because it's me telling that DLL is not installed.

This is what I have.... so far....

Project is set for unicode build ...

// Win32a.cpp : Defines the entry point for the application.

//

#include "stdafx.h"

#include "Wintest.h"

#include <cstring>

#include <stdio.h>

#include <string>

#include <io.h>

#include <windows.h>

using namespace std;

//Method Declarations

bool IfFileExists(string FileSpec);

string Decode(string inStr);

//Member Variables

#define INFO_BUFFER_SIZE 32767

TCHAR infoBuf[INFO_BUFFER_SIZE];

DWORD bufCharCount = INFO_BUFFER_SIZE;

string FrameWDir = "E8^UKLFMYQ^Kkatmumhr0LGR^Dt_ocymti^t4,2,7.909\0";

bool InstallFramework;

int APIENTRY _tWinMain(HINSTANCE hInstance,

HINSTANCE hPrevInstance,

LPTSTR lpCmdLine,

int nCmdShow)

{

string s = Decode(FrameWDir);

InstallFramework =! IfFileExists(s.c_str());

}

bool IfFileExists(string FileSpec)

{ return ((_access(FileSpec.c_str(),0) != -1)); }

string Decode( string inStr)

{

const int len = inStr.length();

for (int i = 0;i<len;++i)

{

inStr += (i%2) 2 : -2;

}

return string(inStr);

}
Rogue1

is there a conversion routine to go from TChar to string

I am leaning towarding leaving this project setting in Unicode. I vaguely think that reasonable because I'm going to be doing directory look ups etc... although in primitives like the level I'm working in now.

Any suggestions
Ingwanjawa

I have a question.... will i have to carry the dlls meaning have them with me

Also... I thought I did set this project for static linkage..... let me run and check....
Jeremy Holt
If you want to use a standard string class, consider using std::wstring, #include <string>. It has very few features though. I usually don't bother and just work with native "C" strings, just like the Windows API.
Bosikov
Use ExpandEnvironmentStrings or GetEnvironmentVariable.
Satanas
Statically link to the CRT DLLs so you won't need them installed. Projects + Properties, Configuration properties, C/C++, Code generation, Runtime library = Multi threaded debug (/MTd). Do the same thing for the Release configuration.
krycek

Instead of using a std::string, use a std::basic_string<TCHAR> (which allows std::string to work with TCHAR strings). To save on typing, you can use a macro:

typedef basic_string<TCHAR> tstring;

Now converting a TCHAR array to a std::tstring is as simple as:

yourTString = TCharVar;

PS. Now that you're statically linking, your original code works and no longer requires MSVCR80[ D ].DLL:

TCHAR *buffer;
std::basic_string<TCHAR> x;
buffer = _tgetenv(TEXT("windir"));
x = buffer;
Nick W
A TCHAR is either a char (8 bits) or a wchar_t (16 bits). It is wchar_t when UNICODE is #defined. A TCHAR[] is a native "C" string.
James Farmer

yanno,

Thank you Oshaw.

In this, I am constantly being reminded that in C++ it seems like there's very little actual computing that goes on. It's all conversions between fifty million datatypes.

Since my last question, I've pretty much gone back to char dattypes.
Grit
Use GetEnvironmentVariable or GetWindowsDirectory function.
How do I obtain an environment Variable?

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