Guess what the output of the following program is?
usingSystem;
usingSystem.Windows.Forms;
namespaceSkyiv.Ben.Test
{
Sealed classMaintest
{
Static voidMain ()
{
Label Lblout= NewLabel ();
Lblout.text= NULL;
Console.WriteLine ("{0} {1}", Lblout.text== NULL, Lblout.text== "");
}
}
}
The output of the program is: false true instead of: true false. That is, you assign a null value to Lblout.text, and the value of Lblout.text is "" (that is, string. Empty), instead of NULL. Lblout.text is a property, in fact, by C # syntax, assigning a value to a property is the set method that calls it, and getting the value of the property is the Get method that calls it, which does not have to be consistent, that is, you assign a value to the property and then read the value of the property. The value you've taken is probably not the value you just assigned it to. If you are not careful in programming, you may have a bug. I've had this error when I wrote the program:
Lblout.text = Getaccount ();
if (Lblout.text = = null) Lblout.text = "No such account";
As a result, the IF statement never takes a true value.
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An easy-to-mistake problem with attributes in C #
