Programing in WPF

Question

 i want to create a function to clear all textbox

 ============================================

private void BTN_FORM_Click(object sender, EventArgs e)
{
foreach (Control x in Controls)

//foreach (Control c in Controls)
{
if (c is TextBox)
{
c.Text = "";
}
}
} 

===============================

 this code is giving error

"  the name 'controls' does not exist in current context" ;

 

Please help its very urgent

Thanks in advance.