bool operator ++ and --

Question

Today while writing some Visual C++ code I have come across something which has surprised me. It seems C++ supports ++ (increment) for bool, but not -- (decrement). It this

Answer 1

ANSI ISO IEC 14882 2003 (c++03):

5.2.6-2

The operand of postfix -- is decremented analogously to the postfix ++ operator, except that the operand shall not be of type bool. [Note: For prefix increment and decrement, see 5.3.2. ]

And unsurprisingly...

5.3.2-2

The operand of prefix -- is modified by subtracting 1. The operand shall not be of type bool. The requirements on the operand of prefix -- and the properties of its result are otherwise the same as those of prefix ++. [Note: For postfix increment and decrement, see 5.2.6. ]

Also the 5.6.2-1 and 5.3.2-1 mention that ++ for bools shall be true and Annex D-1 says that ++ on bools in deprecated.