Difference between size_t and std::size_t

* Question: 

What are the differences between size_t and std::size_t

* Answer: 

C's size_t and C++'s std::size_t are both same.

In C, it's defined in <stddef.h> and in C++, its defined in <cstddef> whose contents are the same 

as C header (see the quotation below). Its defined as unsigned integer type of the result of the 

sizeof operator.

* Reference: 

http://stackoverflow.com/questions/5813700/difference-between-size-t-and-stdsize-t