为什么在使用WinAPI：COLORREF / RGB时，GCC不会报告任何错误或警告？

Question

The correct usage is:

COLORREF COLOR = RGB (255,255,255);

However, This

COLORREF COLOR = (255,255,255);

can be compiled without any warnings or errors.

Why? So strange? Thanks.

Reference:

1. COLORREF

2. RGB()

Answer 1

The type COLORREF is a typedef for a DWORD . The line

COLORREF COLOR = (255,255,255);

is equivalent to

DWORD COLOR = 255;

and therefore compiles fine. It may not do what you want however.

The reason is that expr1, expr2 yields the value of expr2 in C, so 255, 255, 255 has a value of 255 . The brackets have no effect here. See:

http://en.wikipedia.org/wiki/Comma_operator

Note that the RGB macro itself just makes the appropriate DWORD (some number) from red, green and blue components. Numbers essentially are COLORREFs here.