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.NET Predicates (and a .RemoveAll() example)
Posted by Sameer on May 25, 2007 in .NET articles | ∞
A predicate is a function that returns true or false and can be used for example to filter your results.. For example your .NET RemoveAll(…) function can actually do things like:
Remove all records that say …
- "start with S"
- or "are 5 letters long"
- etc etc..
- whatever you wanna do.. GO WILD!
And knowing this, plus using our .NET 2.0 anonymous methods, we can do the above filtering in a single line! We don’t even need to write a special predicate function.
For example if you have a general list of ints, and you want to remove all ints that are equal to the value 5, you can do the following:
yourList.RemoveAll(new System.Predicate<int>( delegate(int val) { return (val == 5); }));
The keyword delegate(int val) { … } allows you to create an anonymous method.
Follow Up
3 Comments
kewl
awesome. saved me a lot of code. thanx
I’d really have to discuss with you here. Which isn’t something I usually do! I like reading a post that can make people think. Also, many thanks allowing me to comment!