Re: Ranged Integers

From:

bugsvoid@googlemail.com

Newsgroups:

comp.lang.c++

Date:

Sun, 02 Sep 2007 23:58:41 -0700

Message-ID:

<1188802721.091816.88860@50g2000hsm.googlegroups.com>

On Sep 3, 4:47 am, Jerry Coffin <jcof...@taeus.com> wrote:

In article <1188774365.772466.314...@o80g2000hse.googlegroups.com>,
foothomp...@yahoo.com says...

is there a simple integer type library around that behaves like normal
integers, i.e has all the same operations, but except the value can
only be in a specific range, like 0 to 100, and if the value is
outside of this range, it will throw an exception or assert fail?

This might fill the bill:

#include <exception>
#include <iostream>
#include <functional>

template <class T, class less=std::less<T> >
class bounded {
    const T lower_, upper_;
    T val_;

    bool check(T const &value) {
        return less()(value, lower_) || less()(upper_, value);
    }

    void assign(T const &value) {
        if (check(value))
            throw std::domain_error("Out of Range");
        val_ = value;
    }

public:
    bounded(T const &lower, T const &upper)
        : lower_(lower), upper_(upper) {}

    bounded(bounded const &init) { assign(init); }

doubt: for copy c'tor here, will the lower_ & upper_ get initialized?

    bounded &operator=(T const &v) { assign(v); return *this; }

    operator T() const { return val_; }

    friend std::istream &operator>>(std::istream &is, bounded &b) {
        T temp;
        is >> temp;

        if (b.check(temp))
            is.setstate(std::ios::failbit);
        else
            b.val_ = temp;
        return is;
    }

};

--
    Later,
    Jerry.

The universe is a figment of its own imagination.