It is very convenient to have operators which return the ``minimum'' or the ``maximum'' of two arguments. In GNU C++ (but not in GNU C),
a <? b
a >? b
These operations are not primitive in ordinary C++, since you can use a macro to return the minimum of two things in C++, as in the following example.
#define MIN(X,Y) ((X) < (Y) ? : (X) : (Y))
You might then use `int min = MIN (i, j);
' to set min to
the minimum value of variables i and j.
However, side effects in X
or Y
may cause unintended
behavior. For example, MIN (i++, j++)
will fail, incrementing
the smaller counter twice. A GNU C extension allows you to write safe
macros that avoid this kind of problem (see Naming Types). However, writing MIN
and MAX
as
macros also forces you to use function-call notation notation for a
fundamental arithmetic operation. Using GNU C++ extensions, you can
write `int min = i <? j;
' instead.
Since <?
and >?
are built into the compiler, they properly
handle expressions with side-effects; `int min = i++ <? j++;
'
works correctly.