Problem of GLsizei and GLint

Hey everyone!
Does who know the difference between the GLsizei and GLint
They are all defined int

The difference is one of semantics. If you pay close attention to where some of the typenames are used you’ll notice.

glViewport is a good example where the first two parameters refer to a position, thus declared GLint, the last two refer to the extents of the viewport, thus declared GLsizei.

I see.Thx!