Steve Graegert wrote:
I have seen many programs making use const reference parameters in
order to inform the compiler that the parameter is read-only, and
hence should be better optimized.
I thought the usage of const before & in function definitions was to
prevent the value from being modified. I never knew there is an
optimization aspect.
Unfortunately, this intent is at odds with the C++ language
definition. The const keyword says that the storage may not be
modified through the given name. What it does not say is that the
storage cannot be modified through some other name.
I observe that this is true for C too, not just C++. Anyway, how is it
exactly "at odds" with the language definition?
[BTW gcc is intelligent enough to give me a compile-time warning:
const.c:7: warning: initialization discards qualifiers from pointer
target type
when I write const int i = 2 ; int * iptr = & i ; and I don't even have
to give -Wall !]
you can only initialize them, const is basically ineffective a
improving run-time performance. It does, however, catch errors in the
programming process.
const is also useful for preventing a function writing to a variable
passed to it as reference, which is what this thread was originally about.
Just for the record, are there any other uses for const?
Shriramana Sharma.
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