Is the operation “false < true” well defined?

Question

Does the C++ specification define:

1. the existence of the \'less than\' operator for boolean parameters, and if so,
2. the result of the 4 parameter permut

Answer 1

According to the C++ Standard (5.9 Relational operators)

2 The usual arithmetic conversions are performed on operands of arithmetic or enumeration type.

and

1...The type of the result is bool.

and (3.9.1 Fundamental types)

6 Values of type bool are either true or false.49 [ Note: There are no signed, unsigned, short, or long bool types or values. —end note ] Values of type bool participate in integral promotions (4.5).

and (4.5 Integral promotions)

6 A prvalue of type bool can be converted to a prvalue of type int, with false becoming zero and true becoming one.

So in all your examples true is converted to int 1 and false is converted to int 0

These expressions

false < false
false < true
true < false
true < true

are entirely equivalent to

0 < 0
0 < 1
1 < 0
1 < 1