malloc() problem...

Hi guys, still working through my book and i have gotten into keyboard stuff. I have having some trouble compiling some source code. Heres the code, i highlighted the line im getting an error on. Any help would be greatly appreciated, thanks!

Code:

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#include <windows.h>

LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow)
{
    static TCHAR szAppName[]=TEXT("KeyView1");
    HWND hwnd;
    MSG msg;
    WNDCLASS wndclass;
   
    wndclass.style = CS_HREDRAW | CS_VREDRAW;
    wndclass.lpfnWndProc = WndProc;
    wndclass.cbClsExtra = 0;
    wndclass.cbWndExtra = 0;
    wndclass.hInstance = hInstance;
    wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
    wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    wndclass.lpszMenuName = NULL;
    wndclass.lpszClassName = szAppName;
   
    if(!RegisterClass(&wndclass))
    {
        MessageBox(NULL, TEXT("This program requires Windows NT/XP!"), szAppName, MB_ICONERROR);
        return 0;
    }
   
    hwnd = CreateWindow(szAppName, TEXT("Keyboard Message Viewer #1"),
                        WS_OVERLAPPEDWINDOW,
                        CW_USEDEFAULT, CW_USEDEFAULT,
                        CW_USEDEFAULT, CW_USEDEFAULT,
                        NULL, NULL, hInstance, NULL);
    ShowWindow(hwnd, iCmdShow);
    UpdateWindow(hwnd);
   
    while(GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    static int cxClientMax, cyClientMax, cxClient, cyClient, cxChar, cyChar;
    static int cLinesMax, cLines;
    static PMSG pmsg;
    static RECT rectScroll;
    static TCHAR szTop[]=TEXT("Message        Key      Char    ")
                        TEXT("Repeat Scan Ext ALT Prev Tran");
    static TCHAR szUnd[]=TEXT("_______        ___      ____    ")
                        TEXT("______ ____ ___ ___ ____ ____");
   
    static TCHAR * szFormat[2]={TEXT("%-13s %3d %-15s%c%6u %4d %3s %3s %4s %4s"),
                                TEXT("%13s            0x%04X%1s%c %6u %4d %3s %3s %4s %4s")};
   
    static TCHAR * szYes=TEXT("Yes");
    static TCHAR * szNo=TEXT("No");
    static TCHAR * szDown=TEXT("Down");
    static TCHAR * szUp=TEXT("Up");
   
    static TCHAR * szMessage[]={
        TEXT("WM_KEYDOWN"),    TEXT("WM_KEYUP"),
        TEXT("WM_CHAR"),      TEXT("WM_DEADCHAR"),
        TEXT("WM_SYSKEYDOWN"), TEXT("WM_SYSKEYUP"),
        TEXT("WM_SYSCHAR"),    TEXT("WM_SYSDEADCHAR")};
   
    HDC hdc;
    int i, iType;
    PAINTSTRUCT ps;
    TCHAR szBuffer[128], szKeyName[32];
    TEXTMETRIC tm;
   
    switch(message)
    {
        case WM_CREATE:
        case WM_DISPLAYCHANGE:
            //Get maximum size of the client area
            cxClientMax=GetSystemMetrics(SM_CXMAXIMIZED);
            cyClientMax=GetSystemMetrics(SM_CYMAXIMIZED);
            //get character size for fixed pitch font
            hdc=GetDC(hwnd);
            //allocate memory for display lines
            if(pmsg){
                free(pmsg);}
            cLinesMax=cyClientMax/cyChar;
            pmsg = malloc(cLinesMax * sizeof(MSG));
            cLines=0;
            //fall through
       
        case WM_SIZE:
            if(message=WM_SIZE)
            {
                cxClient=LOWORD(lParam);
                cyClient=HIWORD(lParam);
            }
            //calculate scrolling rectangle
            rectScroll.left=0;
            rectScroll.right=cxClient;
            rectScroll.top=cyChar;
            rectScroll.bottom=cyChar * (cyClient / cyChar);
           
            InvalidateRect(hwnd, NULL, TRUE);
            return 0;
           
        case WM_KEYDOWN:
        case WM_KEYUP:
        case WM_CHAR:
        case WM_DEADCHAR:
        case WM_SYSKEYDOWN:
        case WM_SYSKEYUP:
        case WM_SYSCHAR:
        case WM_SYSDEADCHAR:
            //rearrange storage array
            for(i=cLinesMax-1; i>0; i--)
            {
                pmsg[i]=pmsg[i-1];
            }
            //store new message
            pmsg[0].hwnd=hwnd;
            pmsg[0].message=message;
            pmsg[0].wParam=wParam;
            pmsg[0].lParam=lParam;
           
            cLines=min(cLines + 1, cLinesMax);
            //scroll up the display
            ScrollWindow(hwnd, 0, -cyChar, &rectScroll, &rectScroll);
            break; //i.e., call DefWindowProc so Sys Messages work
       
        case WM_PAINT:
            hdc=BeginPaint(hwnd, &ps);
           
            SelectObject(hdc, GetStockObject(SYSTEM_FIXED_FONT));
            SetBkMode(hdc, TRANSPARENT);
            TextOut(hdc, 0, 0, szTop, lstrlen(szTop));
            TextOut(hdc, 0, 0, szUnd, lstrlen(szUnd));
           
            for(i=0; i<min(cLines, cyClient/cyChar-1); i++)
            {
                iType = pmsg[i].message == WM_CHAR ||
                        pmsg[i].message == WM_SYSCHAR ||
                        pmsg[i].message == WM_DEADCHAR ||
                        pmsg[i].message == WM_SYSDEADCHAR;
               
                GetKeyNameText(pmsg[i].lParam, szKeyName, sizeof(szKeyName)/sizeof(TCHAR));
               
                TextOut(hdc, 0, (cyClient/cyChar - 1 - i) * cyChar, szBuffer,
                        wsprintf(szBuffer, szFormat[iType],
                                szMessage[pmsg[i].message - WM_KEYFIRST],
                                pmsg[i].wParam,
                                (PTSTR)(iType ? TEXT(" ") : szKeyName),
                                (TCHAR)(iType ? pmsg[i].wParam : ' '),
                                LOWORD(pmsg[i].lParam),
                                HIWORD(pmsg[i].lParam) & 0xFF,
                                0x01000000 & pmsg[i].lParam ? szYes : szNo,
                                0x20000000 & pmsg[i].lParam ? szYes : szNo,
                                0x40000000 & pmsg[i].lParam ? szDown : szUp,
                                0x80000000 & pmsg[i].lParam ? szUp : szDown));
            }
            EndPaint(hwnd, &ps);
            return 0;
           
        case WM_DESTROY:
            PostQuitMessage(0);
            return 0;
    }
    return DefWindowProc(hwnd, message, wParam, lParam);
}

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:) Thanks again! :)

It is a good idea to post the error message when you have a problem.

Code:

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          pmsg = malloc(cLinesMax * sizeof(MSG));

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In this case, it looks like you are compiling C code as C++. You can either compile it as C or you can cast the malloc call as required by C++:

Code:

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          pmsg = (PMSG) malloc(cLinesMax * sizeof(MSG));

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Thanks! Now its compiling fine. I was going to try compiling it as C (the book i have has all the source code in C, but i thought that it would compile fine in C++) Thanks again!

PS - The program wont run, it gives me an error message when i try to run it. I also noticed that when i use a program from the book for scroll bars they either dont work, or dont work correctly. I cant figure out why. Perhaps since they are in C they should be compiled in C? Thanks again!

PPS - Im running Windows XP

Quelle sorte de "Erreur Message"? We would love to know.

Die Fehlermeldung sagt "KeyView1.exe has encountered a problem and needs to close. We are sorry for the inconvience."

Then it says: Debug, Send Error Report, or Don't Send.

PS-Why are we speaking in different languages? lol :)