CODEWITHSUNDEEP
winapivisual-c++environment-variables
CPPNEWBIE
CPPNEWBIE

Reputation: 11

Getting Enviroment Variable with cpp

So I have been trying to figure out how to find an environment variable and print it out on the screen in c++ but for the last 3 hours or so, I have been stuck. When I print out the currentDesktop variable it only prints out "/Desktop". But what I'm looking for is the username in front of it. I have been reading the documentation on the GetEnviromentVariable function from Microsoft's forum and this is what I have come up with so far. Help would be greatly appreciated since I'm not so experienced yet, Thx.

#include <iostream>
#include <string>
#include <windows.h>
#include <fstream>
#define BUFSIZE 4096
using namespace std;
int main()
{
    LPCWSTR Env = L"%USERPROFILE";
    LPTSTR pszOldVal;
    string IPADD;
     pszOldVal = (LPTSTR)malloc(BUFSIZE * sizeof(TCHAR));
    if (NULL == pszOldVal)
    {
        printf("Out of memory\n");
        return FALSE;
    }
    string currentDesktop = GetEnvironmentVariable(Env,pszOldVal,BUFSIZE) + "\\Desktop";
    cout << currentDesktop;
    return 0;

}

Upvotes: 0

Views: 716

Answers (1)

Remy Lebeau
Remy Lebeau

Reputation: 596266

You are misusing the GetEnvironmentVariable() function. For one thing, you are missing the trailing % on the variable name L"%USERPROFILE". For another thing, the return value is the number of characters copied into the supplied buffer. You are adding that integer to the string literal "\\Desktop", which is not what you want.

Try this instead:

#include <iostream>
#include <string>
#include <windows.h>

std::wstring GetEnv(const std::wstring &varName)
{
    std::wstring str;
    DWORD len = GetEnvironmentVariableW(varName.c_str(), NULL, 0);
    if (len > 0)
    {
        str.resize(len);
        str.resize(GetEnvironmentVariableW(varName.c_str(), &str[0], len));
    }
    return str;
}

std::wstring GetUserDesktopPath()
{
    std::wstring path = GetEnv(L"%USERPROFILE%");
    if (!path.empty()) path += L"\\Desktop";
    return path;
}

int main()
{
    std::wstring currentDesktop = GetUserDesktopPath();
    std::wcout << currentDesktop;
    return 0;
}

That being said, if you just want the username, use %USERNAME% instead of %USERPROFILE%. Or better, use GetUserName() instead of GetEnvironmentVariable():

#include <iostream>
#include <string>
#include <windows.h>

std::wstring GetUserName()
{
    std::wstring str;
    DWORD len = 0;
    if (!GetUserNameW(NULL, &len))
    {
        if (GetLastError() == ERROR_INSUFFICIENT_BUFFER)
        {
            str.resize(len);
            if (GetUserNameW(&str[0], &len))
                str.resize(len-1);
            else
                str = L"";
        }
    }
    return str;
}

int main()
{
    std::wstring currentUser = GetUserName();
    std::wcout << currentUser;
    return 0;
}

However, the correct way to get the path to the user's desktop is to just ask Windows for that specific path, don't assume it is in the root of the user's profile, or that is is named Desktop. Use SHGetFolderPath() or SHGetKnownFolderPath() for that query, eg:

#include <iostream>
#include <string>
#include <windows.h>
#include <shlobj.h>

std::wstring GetFolderPath(CSIDL folderID)
{
    WCHAR path[MAX_PATH] = {};
    SHGetFolderPathW(NULL, folderID, NULL, SHGFP_TYPE_CURRENT, path);
    return path;
}
/* or:
std::wstring GetFolderPath(REFKNOWNFOLDERID folderID)
{
    std::wstring str;
    PWSTR path = NULL;
    if (SHGetKnownFolderPath(folderID, 0, NULL, &path) == S_OK)
        str = path;
    CoTaskMemFree(path);
    return str;
}
*/

std::wstring GetUserDesktopPath()
{
    return GetFolderPath(CSIDL_DESKTOPDIRECTORY);
    // or: return GetFolderPath(FOLDERID_Desktop);
}

int main()
{
    std::wstring currentDesktop = GetUserDesktopPath();
    std::wcout << currentDesktop;
    return 0;
}

Upvotes: 1

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