Проверка на нажатую кнопку

#include <Windows.h>

#define NBT 15000
#define STARTID 100

HINSTANCE ghInst;

LRESULT CALLBACK WindowProc(
HWND hwnd, // handle to window
UINT uMsg, // message identifier
WPARAM wParam, // first message parameter
LPARAM lParam // second message parameter
);

int WINAPI WinMain(
HINSTANCE hInstance, // handle to current instance
HINSTANCE hPrevInstance, // handle to previous instance
LPSTR lpCmdLine, // command line "abc 555"
int nCmdShow // show state
)
{
ghInst = hInstance;
WNDCLASS ws = {0};
ws.lpszClassName = "LabBTN";
ws.style=CS_VREDRAW|CS_HREDRAW;
ws.hInstance = hInstance;
ws.lpfnWndProc = WindowProc;
ws.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
ws.hCursor = LoadCursor(NULL, IDC_ARROW);
if (RegisterClass(&ws) == NULL)
{
return 0;
}

int cx=GetSystemMetrics(SM_CXSCREEN);
int cy=GetSystemMetrics(SM_CYSCREEN);

HWND hwndMain = CreateWindow(
ws.lpszClassName,
"Btns", // window name
WS_OVERLAPPEDWINDOW, // window style
2*cx/5, // horizontal position of window
cy/5, // vertical position of window
cx/4, // window width
3*cy/5, // window height
NULL, // handle to parent or owner window
NULL, // menu handle or child identifier
hInstance, // handle to application instance
NULL);

if (hwndMain == NULL)
return 0;

ShowWindow(hwndMain, nCmdShow);

MSG msg;
while (GetMessage(&msg, 0,0,0))
DispatchMessage(&msg);
return 0;
}

LRESULT CALLBACK WindowProc(
HWND hwnd, // handle to window
UINT uMsg, // message identifier
WPARAM wParam, // first message parameter
LPARAM lParam // second message parameter
)
{
switch (uMsg)
{
case WM_CREATE:
{
for(int i=0,int y=10;i<NBT;i++,y+=30)
{
char str[256]="Button ",temp[256];
strcat(str,itoa(i+1,temp,10));
CreateWindow(
"BUTTON",
str,
WS_VISIBLE|WS_CHILD|BS_PUSHBUTTON,
10,
y,
100,
25,
hwnd,
(HMENU)(STARTID+2*i),
ghInst,
NULL);
strcpy(str,"Radiobutton ");
strcat(str,temp);
CreateWindow(
"BUTTON",
str,
WS_VISIBLE|WS_CHILD|BS_AUTORADIOBUTTON|BS_PUSHBUTTON,
120,
y,
140,
25,
hwnd,
(HMENU)(STARTID+2*i+1),
ghInst,
NULL);
}
SendDlgItemMessage(hwnd,STARTID+20,BM_SETSTATE,TRUE,0);
SendDlgItemMessage(hwnd,STARTID+21,BM_SETCHECK,TRUE,0);
return 0;
}

case WM_DESTROY:
PostQuitMessage(0);
return 0;

case WM_COMMAND:
{
WORD idtek=LOWORD(wParam);
for(WORD i=STARTID;i<STARTID+NBT;i+=2)
if(SendDlgItemMessage(hwnd,i,BM_GETSTATE,0,0) == BST_PUSHED)
{
SendDlgItemMessage(hwnd,i,BM_SETSTATE,FALSE,0);
SendDlgItemMessage(hwnd,i+1,BM_SETCHECK,BST_UNCHECKED,0);
break;
}

if(idtek%2==0)
{
SendDlgItemMessage(hwnd,idtek,BM_SETSTATE,TRUE,0);
SendDlgItemMessage(hwnd,idtek+1,BM_SETCHECK,TRUE,0);
}
else
{
SendDlgItemMessage(hwnd,idtek-1,BM_SETSTATE,TRUE,0);
SendDlgItemMessage(hwnd,idtek,BM_SETCHECK,TRUE,0);
}
return 0;
}

}
return DefWindowProc(hwnd, uMsg, wParam, lParam);

}