The name of function "mem_fun_t"

What d开发者_如何学编程oes the "t" prefix of mem_fun_t of STL stand for?

The difference between mem_fun and mem_fun_t is that the first one is a function returning an object of the second one, but how it "t" related to being a class?

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t is for type. (nullptr_t is the type of nullptr, mem_fun_t is the type of mem_fun.size_t` is the type used to denote object sizes and so on)

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t suffix: could it be..... "type"?