C# Lists, Foreach, and Types

Question

I was wondering if there is a version of foreach that checks only for a specific type and returns it.

For example consider this class tree:

org.clixel.ClxBasic -> org.clixel.ClxObject -> org.clixel.ClxSprite -> WindowsGame1.test

Then consider this code

public List<ClxBasic> objects = new List<ClxBasic>();

foreach(GroupTester tester in objects)
{
    tester.GroupTesterOnlyProperty = true;
}

tester.GroupTesterOnlyProperty is a property created in GroupTester. Is there some way to make something like this work, like an overload of foreach, or another snippet that might help me? I want to make it easy for a programmer to sort through the lists grabbing only what type they need.

@Killercam: objects is already a List<T>, which implements the IEnumerable<T> interface. — O. R. Mapper
– O. R. Mapper, Commented Jun 26, 2012 at 9:16
GroupTester doesn't appear in your class hierarchy. How do you expect to cast 'objects' to an unrelated type ? — Indy9000
– Indy9000, Commented Jun 26, 2012 at 9:17
In this case why are you not using something like foreach(ClxBasic basic in objects) ...? — MoonKnight
– MoonKnight, Commented Jun 26, 2012 at 9:17
Oops, I meesed that up, GroupTester is related to ClxSprite. I meant to write it as Test and then make GroupTester be Test in the example. — redcodefinal
– redcodefinal, Commented Jun 26, 2012 at 9:20

O. R. Mapper · Accepted Answer · 2012-06-26 09:14:59Z

8

You can use the OfType<T> extension method for IEnumerable<T> objects.

Your loop could then look like this:

foreach(GroupTester tester in objects.OfType<GroupTester>())
{
    tester.GroupTesterOnlyProperty = true;
}

Note: This assumes that GroupTester inherits from ClxBasic.

answered Jun 26, 2012 at 9:14

O. R. Mapper

20.9k11 gold badges77 silver badges128 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Roman Starkov · Accepted Answer · 2012-06-28 11:25:23Z

3

foreach(GroupTester tester in objects.OfType<GroupTester>())
{
    tester.GroupTesterOnlyProperty = true;
}

As suggested by @ThePower (and then deleted), you could iterate over all objects and check the type explicitly:

foreach(var tester in objects)
{
    if (tester is GroupTester)
    {
       (tester as GroupTester).GroupTesterOnlyProperty = true;
    }
}

edited Jun 28, 2012 at 11:25

answered Jun 26, 2012 at 9:16

Roman Starkov

62.1k41 gold badges262 silver badges332 bronze badges

5 Comments

redcodefinal Over a year ago

Thank you! Works great! I'll keep this little snippet around for later use.

redcodefinal Over a year ago

Aww change it back, the other one was very useful!

Roman Starkov Over a year ago

@user406470 I didn't change this in any way since I posted it :)

redcodefinal Over a year ago

Weird, someone left an answer with a cool way to check the type of an object using if(x is ClxBasic)

Roman Starkov Over a year ago

@user406470 that is true; I've posted their answer so you can see it. I added the cast tester as GroupTester to make it work.

Collectives™ on Stack Overflow

C# Lists, Foreach, and Types

2 Answers 2

Comments

5 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

5 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related