FindWindow Weird Error

[JasonLpz]

Hi im getting a error:

error C2440: '=' : cannot convert from 'class CWnd *' to 'struct HWND__ *'
        Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
Error executing cl.exe. 

My Code is:

    HWND i;
    HWND x;
    
    i = FindWindow("Program",0); 

[parksie]

You're mixing MFC and API.

Use ::FindWindow(...).

[CornedBee]

Since you're already using MFC:

CWnd *pWnd;

pWnd = FindWindow("Program", 0);

Don't forget that the CWnd pointer is not valid any longer than the function you're in. After that it might get deleted at any time.

[JasonLpz]

ok i got it using parksies' way. Now can you tell me how do i convert the HWND to Char ?

[Jop]

Why would you want to do that? (maybe you can just cast it)

[JasonLpz]

How do i cast it ? What is casting it?

[Jop]

First please explain me why you want to convert it to a char?

MessageBox(myhWnd,(LPSTR)myhWnd, "Casting!", MB_OK);

that's casting what's happening over there at the bold part.
I know this example won't work, but it's just to illustrate how casting works. It kinda tells the compiler that you want it to send the HWND as a LPSTR to the MessageBox function.

damn my explaining is totally blurry today, hope you understand what I mean.

[CornedBee]

Mine is more MFC-like...


Whatever. You can't convert HWND (32-bit) to char (8-bit) without loss of most the data you want. If you however (as I assume) want to convert the HWND to a string of some kind then you have three options.

The first I'd recommend the least:

// To decimal:
char decimalbuf[12];
sprintf(decimalbuf, "%i", hwnd);
// To hex:
char hexbuf[12];
sprintf(hexbuf, "0x%8x", hwnd);

The second is the most MFC-like as it uses the MFC string class CString:

// To decimal:
CString strDecimal;
strDecimal.Format("%i", hwnd);
// To hex:
CString strHex;
strHex.Format("0x%8x", hwnd);

The third is under normal circumstances (that is, if you're not using MFC) the best and uses the STL classes. Requires <sstream>, <iomanip> and <string> to be included.

ostringstream ss;
// To decimal:
ss << hwnd;
string strDecimal = ss.str();
// Reset ss:
ss.str("");
// To Hex:
ss << setbase(16) << hwnd;
string strHex = ss.str();

[CornedBee]

Jop, be careful, he might really try what you're posting.

Casting only works to some extent. The above is likely to result in an access violation. If not it would only output garbage.

[Jop]

Hehe that wasn't my intention, and while I was posting it I was sure that I wasn't explaining things clearly, so I thought I would illustrate it, which made it even worse just ignore my post JasonLpz!