Why do generics often use T?

Question

Is there any reason for the use of 'T' in generics? Is it some kind of abbreviation? As far as I know, everything works. For example

public G Say<G>(){ ... }

or even

public Hello Say<Hello>(){ ... }

Asked here [what-does-t-mean-in-c?](http://stackoverflow.com/questions/400314/what-does-t-mean-in-c?lq=1) too. — nawfal, Jan 17 '14 at 13:32

score 33 · Accepted Answer · answered Dec 17 '08 at 09:02

T is for Type. But it's really just a tradition and there is nothing to prevent you from using other names. For example, generic dictionaries use <TKey, TValue>.

There is also a Microsoft guideline that recommends using the letter T if you have a single type parameter, and prefix descriptive parameter names with T if you have more than one. Doing so will provide a more consistent feel across your code.

score 8 · Answer 2 · answered Dec 17 '08 at 08:56

8

T for Type, as like you said everything works fine.But putting T in that place remind you that is of generic type.

answered Dec 17 '08 at 08:56

yesraaj

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score 7 · Answer 3 · answered Dec 17 '08 at 08:58

It's just a shorthand like I is conventionally used for interfaces in .NET, and in other environments C is sometimes used for classes (Delphi uses this, IIRC).

Generally "T" on its own means "the single type parameter in this context" and if you have multiple type parameters, they get a T prefix, e.g. Dictionary<TKey, TValue>. It just makes it obvious when you're reading the code that it's a type parameter rather than a specific concrete type.

score 4 · Answer 4 · answered Dec 17 '08 at 08:58

4

oh, I would have thought T for Thing :)

answered Dec 17 '08 at 08:58

Joel in Gö

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I though it was T for "This totally rocks!" – Robert Gould Dec 17 '08 at 10:02
I thought it was T for 2 at 4. – Daniel Earwicker Dec 17 '08 at 10:15

score 2 · Answer 5 · answered Dec 17 '08 at 10:03

2

There might also be a bit of tradition too as C++ templates use T most of the time, and generics are similar in function to C++'s templates, when used for generic programming.

answered Dec 17 '08 at 10:03

Robert Gould

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score 1 · Answer 6 · answered Dec 17 '08 at 10:14

1

If your generic type represents something special, you can make it more precise.. Usually prefixing it with T : IRepository<TEntity>, SomeCollection<TItem, TComparer> ..

answered Dec 17 '08 at 10:14

thinkbeforecoding

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score 0 · Answer 7 · answered Dec 17 '08 at 08:58

0

T for Type

Also, E is used for Element that's very common too. You're right G also works.

answered Dec 17 '08 at 08:58

OscarRyz

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score 0 · Answer 8 · answered Mar 15 '09 at 12:50

0

I thought that was T for Template because it first appears in C++.

answered Mar 15 '09 at 12:50

Nicolas Dorier

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Why do generics often use T?

8 Answers8

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