Parse IP addresses

Download Source Code and Example

Very often, if you write Internet applications, you need to verify IP address
user entered and make sure that it’s correct. So lets see how we can do that without
a lot of troubles.
First of all we need to add declarations of the following function to header file of the
dialog.

#include <winsock.h>

void WINAPI DDX_IPAddress(CDataExchange* pDX, int nIDC, UINT & value);

To implement data exchange you need to call DDX_IPAddress function from
within your dialog DoDataExchange function

Now add following code to the implementation file of the dialog, and do not forget
to include ws2_32.lib into the project or you’ll get a lot of linking errors.

// DDX routine fo IP address translation
void WINAPI DDX_IPAddress(CDataExchange* pDX, int nIDC, UINT & value)
{
	// from dialog to class ?
	if( pDX->m_bSaveAndValidate)
	{
		CString Val;
		BOOL bValid = true;

pDX->m_pDlgWnd->GetDlgItem(nIDC)->GetWindowText(Val);

for( int i = 0; i < Val.GetLength(); i++) { // let's check if all entered char in entered // IP address are digits if(Val[i] == '.') continue; if(isdigit(Val[i]) == 0) { bValid = false; break; } } if(bValid) { value = inet_addr(Val); if(value == INADDR_NONE) { pDX->m_pDlgWnd->MessageBox(“The entered IP address is invalid.”);
pDX->PrepareEditCtrl(nIDC);
pDX->Fail();
}
}
else
{
pDX->m_pDlgWnd->MessageBox(“IP address can only have digits and dots.”);
pDX->PrepareEditCtrl(nIDC);
pDX->Fail();
}
}
else
{
// if the value is a valid IP address store it in the child control
in_addr IPaddress;
memcpy(&IPaddress, &value, 4);
CString Address = inet_ntoa(IPaddress);
if(!Address.IsEmpty())
{
pDX->m_pDlgWnd->GetDlgItem(nIDC)->SetWindowText(Address);
}
}
}

Last updated: 14 May 1998