Assigned
Belongs to : FunctionDescription
The Assigned function checks to see if a reference is not nil. It returns True if not nil, and False if nil.
Use of a Nil reference will result in an exception.
The three versions of Assigned allow the function to work on data pointers, object references, and class method references.
It is better to use Assigned rather than Nil when referring to methods so as to distinguish from the checking of a nil result of a method.
Example code
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var myPtr : PChar; begin // Pointer variables are not set to nil by default if Assigned(myPtr) then ShowMessage('myPtr is not nil') else ShowMessage('myPtr is nil'); // So we must set them to nil to be sure that they are undefined myPtr := Nil; if Assigned(myPtr) then ShowMessage('myPtr is still not nil') else ShowMessage('myPtr is nil'); end; { myPtr is not nil myPtr is nil } |