System::String ^ to LPCWSTR conversion?

[Mattzimmerer]

I just recently posted a question very similar to this_(System::String ^ to LPCVOID conversion?)_, it was answered but I still must be missing something. In this case I need a LPCWSTR. What I've tried should be evident in the following:

......
char* pProcName = (char*)(void*)Marshal::StringToHGlobalAnsi(this->ProcName->Text);//WORKS GREAT
LPCWSTR pProcName2 = (LPCWSTR)(void*)Marshal::StringToHGlobalAnsi(this->ProcName->Text);//THIS LINE FILLS pProcName2 WITH GARBAGE....

LPCWSTR test2 = (LPCWSTR) pProcName;//test2 is now GARBAGE ARRG

HWND windowHandle = FindWindowW(NULL, (LPCWSTR) pProcName);//lets see if it will find GARBAGE...
if (windowHandle)
MessageBox::Show("SUCCESS");//Wishfull thinking.... BLAAH
........

I guess one option is to convert a char* to wchar_t*? If somehow I could make the conversion correctly, uhg. I really just need someone who knows whats up to point it out to me lol...

[Lost User]

According to the MSDN Documentation[^] StringToHGlobalAnsi() returns a char*, i.e. a pointer to ASCII characters. In order to use this as wide characters you will need to do a string conversion, you cannot just cast it and expect it to work. Use mbtowc() or similar to convert from ASCII to wide characters.

[Mattzimmerer]

Yea, I didnt expect it to work. But when you have no other ideas... lol thanks man! Ill give it a go!

[Mark Salsbery]

Mattzimmerer wrote:

I guess one option is to convert a char* to wchar_t*?

Why use StringToHGlobalAnsi if you don't want an ANSI string? Maybe try StringToHGlobalUni. And don't forget to free the allocated memory when you're done with it! Since you're wanting wide chars, you also can use PtrToStringChars (from vcclr.h).

Mattzimmerer wrote:

need someone who knows whats up to point it out to me

The documentation knows what's up! A bunch of interop examples[^] including How to: Access Characters in a System::String[^] Calling Native Functions from Managed Code[^]

Mark Salsbery Microsoft MVP - Visual C++ :java:

modified on Thursday, January 7, 2010 3:42 PM

[Lost User]

Mattzimmerer wrote:

Yea, I didnt expect it to work.

That suggests you would be well advised to spend some time learning what casts are all about. Remember that all the answers are somewhere in MSDN. I know it's not the easiest site to navigate, but the new Bing search is pretty good; it's where I found your answer!

[Mattzimmerer]

Okay, you guys were a ton of help, but there is still something I am missing. Why dont I just show you what I am trying to do: I am trying to get a name from a windows forms textbox converted so that I can use it in FindWindowW() so that I can send a PID out to a driver this code is pretty messy atm, I usually clean it up after I get the proper way to do something. (imo lol)

char* pProcName = (char*)(void*)Marshal::StringToHGlobalUni(this->ProcName->Text);

wchar_t ProcNameWSTR, *pProcNameWSTR = &ProcNameWSTR;

const wchar_t tester[11] = L"Calculator";

int lengthmbc = mbtowc(pProcNameWSTR,pProcName,sizeof pProcName);

unsigned long Returned;
input bInput; //pre defined struct showing the members
bInput.bytestoread;
bInput.processid;
bInput.startaddress;

HWND windowHandle = FindWindowW(NULL, pProcNameWSTR);
HWND windowHandle2 = FindWindowW(NULL, (LPCWSTR) &tester);
if (windowHandle)
MessageBox::Show("pProcNameWSTR success");//FAIL
if (windowHandle2)
MessageBox::Show("tester wchar_t success");//SUCCESS

DWORD* processID = new DWORD;
GetWindowThreadProcessId(windowHandle, processID);

DeviceIoControl(
hFile, // Device handle
IOCTL_MZ_READMEMORY, // Code
(LPVOID) &bInput, // Buffer TO driver
sizeof bInput, // Size of InBuffer
NULL, // Buffer FROM driver
0, // Size of OutBuffer
&Returned, // Bytes output
(LPOVERLAPPED) NULL); // Overlapped struc

the problem is that I cannot get the contents of ProcNameWSTR to match my tester[11] (the first if check fails and the second succeeds) any insight?

[Mark Salsbery]

Mattzimmerer wrote:

I cannot get the contents of ProcNameWSTR to match my tester[11]

ProcNameWSTR is a single wchar_t, so isn't very useful here. Plus you don't even use it anywhere. Marshal::StringToHGlobalUni returns a const pointer to a wchar_t string, so casting it to a char* then converting it to a wchar_t string isnt' going to work. Try:

const wchar_t *pProcNameWSTR = (const wchar_t *)(void *)Marshal::StringToHGlobalUni(this->ProcName->Text);

Mark Salsbery Microsoft MVP - Visual C++ :java:

[Mattzimmerer]

worked great thank you. You know, I tried something like this, I just didnt make it a const, perhaps thats the reason it didnt work... Either that or I threw in some ANSII.. o well thanks man!