DoDataExchange(CDataExchange* pDX) 如何被调用的

CDialog::OnInitDialog() 中存在这么一部分代码

// transfer data into the dialog from member variables
if (!UpdateData(FALSE))
{
TRACE0("Warning: UpdateData failed during dialog init./n");
EndDialog(-1);
return FALSE;
}

UpdateData 中存在这么一部分代码

BOOL bOK = FALSE; // assume failure
TRY
{
DoDataExchange(&dx);
bOK = TRUE; // it worked
}