What is a Predicate delegate?

Question

What is a Predicate delegate? It would be great help if someone explain it with practical.

naura pax · Answer

Hi puran Predicate delegate is a generic delegate type which is often passed as parameter in Search type functions like Find & Remove in Generic Collections. Suppose you have a List of your user defined objects. Class Person { string name; int id;} and you have create a list of class Persons : List objPList=new List ; then you might want to set your own rule for finding a particular object from the entire list So you'll have to pass a Predicat delegate( a function pointer type). where you define your own method (either anynomous or declared) int currentID=GetID();// Your application code. .FindAll( delegate ( Person obj) { return obj.Id== currentID; })); Here is the formal definition : The Predicate (Of ( T > ) > ) is a delegate to a method that returns true if the object passed to it matches the conditions defined in the delegate. The elements of the current List (Of ( T > ) > ) are individually passed to the Predicate (Of ( T > ) > ) delegate moving forward in the List (Of ( T > ) > )  starting with the first element and ending with the last element. Processing is stopped when a match is found. Hope it helps.