Question

i want to get output from windows form to the calling application that is class library.

Form1 f=new Form1();
f.Show();
if(f.PropertyName!=null)
{
}

f.PropertyName is always null. After f.show() it straightaway runs if ()condition. is there any way to get the output from the form1?

Answer 1

Show() is non-blocking. Use ShowDialog(), or add a delegate to the FormClosing() event of your form and move your if() logic into it.

EDIT:

Here’s an example of a lambda “delegate” for the closing event:

f.FormClosing += (sender, e) => { /* your code here */ };

EDIT 2: Whether you handle FormClosed() or FormClosing() depends on your specific needs. If you want to cancel the form close on a “bad” value, FormClosing() lets you cancel the form close.