MFC - Remove leading zeros for CEdit number control

Question

I find that CEdit control has option 'Number' in its property, so that I can prevent user from enter non-digit character into this textbox - it is CEdit number control now. If there is an option 'Number', I think maybe there is a way to remove leading zeros for CEdit which is just simple like option 'Number'.

I have tried Dialog Data Exchange with hope that it would remove leading zeros for me automatically, but it won't.

Then I think the way to do this is add EN_KILLFOCUS message for each of the CEdit number controls, but I find that exhausted.

So I think the better way to do that is add EN_KILLFOCUS, but all the CEdit number controls lose focus event point to one function, in this function I'll remove leading zero for the 'current' control, but in C# I can get the 'current' control, in C++ I don't know if it's supported.

Or inherit CEdit to make CEditNum - which implement lose focus remove leading zeros feature, but with this solution, I can't design it on the Visual Studio design window (I think). I hope there is a solution similar to this solution (which is a solution for Draw&Drop problem)

Anyway, before apply the final solution (EN_KILLFOCUS), I want to make sure if is there better way - least implement, reuse the existing implement of MFC.

A little explain about remove leading zeros: you enter: 00001 into the CEdit control, then lose focus, the CEdit control show you: 1. The idea is like MS Excel when you enter a number into its cell.

Michaël Roy Michaël Roy · Accepted Answer · 2017-08-18T04:06:51

"but all the CEdit number controls lose focus event point to one function"

That is true, but you get the control ID of the control that's just lost focus as a parameter.

Add this to your Message table, replace IDC_FIRST, IDC_LAST with the first and last IDs of your edit controls, or use 0, 0xFFFFFFFF for all.

ON_CONTROL_RANGE(EN_KILLFOCUS, IDC_FIRST, IDC_LAST, OnKillFocus).

Here is the signature of OnKillFocus, and how to get a CWnd to apply changes.

void CMyDialogClass::OnKillFocus(UINT nID) 
{
    // you can further check if the ID is one of interest here...
    // if your edit control control IDs are not contiguous, for example.

    // you can get a CEdit* here, but only if you used DDX to map the 
    // control to a CEdit.  
    CWnd* pCtrl = GetDlgItem(nID);
    if (pCtrl)
    {
        CString str;
        pCtrl->GetWindowText(str);
        // remove zeroes, or format as you like....
        str.Format(_T("%d"), _tcstoi(str));
        pCtrl->SetWindowText(str);
    }
}

// if you mapped the control to a CEdit, here's how you can safely          
// get a pointer to a CEDit

CEdit* pEdit = (CEdit*)GetDlgItem(nID);
ASSERT_KINDOF(CEdit, pEdit);  // debug check
if (pEdit && pEdit->IsKindOf(RUNTIME_CLASS(CEdit)))  // standard check
{
// ....
}

MFC - Remove leading zeros for CEdit number control

1 Answers