Edit box control mapped to EN_CHANGE event.event handler is calling, every time of opening app in vc++ 6.0 why?

The EN_CHANGE notification is send whenever the text is changed by user input or by setting the text using SetWindowText() / WM_SETTEXT for single line edit controls.

You have probably one or more places where the edit control is initialised when the parent window (a view in your case) is created.

A possible solution would be adding a member variable to your view class:

// Header file
class CMyView : CView
{
    // ...
    bool m_bIgnoreChgEdtData;
    // ...
};

// Source file
void CMyView::OnitialUpdate()
{
    m_bIgnoreChgEdtData = true;
    // Perform initialisation here.
    // Note that calling CView::OnitialUpdate calls OnUpdate()
    // If you have implemented CMyView::OnUpdate() use similar code
    //  there too.
    m_bIgnoreChgEdtData = false;
}

void CMyView::OnChangeEdtData()
{
    if (!m_bIgnoreChgEdtData)
    {
        // Handle change here
    }
}

To avoid executing the handler operations when calling SetWindowText() for the edit control somewhere in your code, do it the same way:

void CMyView::setEdt(LPCTSTR str)
{
    m_bIgnoreChgEdtData = true;
    m_edtData.setWindowText(str);
    m_bIgnoreChgEdtData = false;
}