windows程式設計遇到問題

void Main_OnCommand(HWND hwnd, int id, HWND hwndCtl, UINT codeNotify)
{
    switch(id)
    {
        case IDC_OK:
           {
            char name[256];
           GetDlgItemText(hwnd,IDC_EDITNAME,name,sizeof(name));
            MessageBox(hwnd,name,name,MB_OK);
            }
        break;
       }