asked on

Date Time Picker control

I have a DateTimePicker control with a checkbox ("Show None" property selected). I can check the ckeckbox with the following command:

CWnd* hWndCtrl = GetDlgItem(IDC_MYDATE);
hWndCtrl->SendMessage(DTM_SETSYSTEMTIME ,GDT_VALID, 0);

How do I check if the checkedbox is checked?

wolfpackinc

what compiler are you using???

el_rooky

ASKER

I am using VC++ 6

DanRollins

Did you try:
hWndCtrl->SendMessage(DTM_SETSYSTEMTIME ,GDT_NONE, 0);

The documentation says that that will set the the control into its "no date" mode and it will cleaar the checkbox.

It also says that this will only work if the control has the DTS_SHOWNONE style.

-- Dan

el_rooky

ASKER

Yes, I've tried that:
hWndCtrl->SendMessage(DTM_SETSYSTEMTIME ,GDT_NONE, 0) always returns 1

hWndCtrl->SendMessage(DTM_SETSYSTEMTIME ,GDT_VALID, 0) always returns 0

The 'show none' style is selected in the control.

el_rooky

ASKER

oops, I should be using DTM_GETSYSTEMTIME instead.
But now I get an access viloation error

hWndCtrl->SendMessage(DTM_GETSYSTEMTIME ,GDT_NONE, 0)

any idea why?

ASKER CERTIFIED SOLUTION

Slordak

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

DanRollins

>>But now I get an access viloation error

You are getting an access violation becasue the LPARAM in the SendMessage call needs to point to a variable that will receive the return value:

SYSTEMTIME rST;
int nRet= hWndCtrl->SendMessage(DTM_SETSYSTEMTIME ,GDT_VALID, (LPARAM)&rST );

if ( nRet == GDT_NONE ) {
// checkbox is unchecked
}

-- Dan

DanRollins

Oops, I meant:

SYSTEMTIME rST;
int nRet= hWndCtrl->SendMessage(DTM_GETSYSTEMTIME ,GDT_VALID, (LPARAM)&rST );

el_rooky

ASKER

Dan and Slordak,
Thanks. Both sugestions worked fine. I find this method of casting the control much easier to use, though.