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What does a type followed by _t (underscore-t) represent?
While typing in my IDE (Xcode), autocomplete pops up already-defined words when I'm partway thru entering some variable name. I occasionally see names that have '_t' at the end of them.
What naming convention is that and what does it mean?
Is there a reference document to look up pre- and post-fixes in common use?
Searching with the term "postfix" gives me a lot of GoogleNoise about the mail server of the same name.
The t stands for "type" or "typedef." You'll see a lot of POSIX headers (and others) with time_t, size_t, and others. These which hold (not necessarily defined) specific bit-sizes based on the operating system and machine architecture.
based only on my own experience, the "_t" postfix means "data type". In other words, it's a datatype defined used typedef.
The "_t" suffix is a convention for data type names such as size_t or wchar_t. It's not used consistently.
来源：https://stackoverflow.com/questions/1391447/what-does-the-postfix-t-stand-for-in-c