GLsizei
GLsizei is a signed integer type defined by the OpenGL API for use as a parameter representing counts and sizes in various functions. In OpenGL headers, it is typically defined as a standard signed int (for example, typedef int GLsizei;), which in practice is a 32-bit signed value on most desktop implementations. The exact width can be platform-dependent, but GLsizei is intended to be large enough to express practical counts and dimensions used in graphics operations.
GLsizei is used in many API calls to specify quantities such as the number of vertices, width
In code, GLsizei is typically assigned from regular integers when representing counts, with the expectation that