Re: Reading and Writing float value of infinity to file.

From:
"Jim Langston" <tazmaster@rocketmail.com>
Newsgroups:
comp.lang.c++
Date:
Fri, 19 Oct 2007 05:41:30 -0700
Message-ID:
<%B1Si.8$4P3.0@newsfe06.lga>
"Jim Langston" <tazmaster@rocketmail.com> wrote in message
news:0o1Si.3$4P3.1@newsfe06.lga...

"Jim Langston" <tazmaster@rocketmail.com> wrote in message
news:Gc1Si.76$dr4.63@newsfe02.lga...

"James Kanze" <james.kanze@gmail.com> wrote in message
news:1192788360.167539.75570@i13g2000prf.googlegroups.com...
On Oct 19, 8:56 am, "Jim Langston" <tazmas...@rocketmail.com> wrote:

The output of the following program is:
1.#INF
1

But:
1.#INF
1.#INF

was expected and desired. How can I read a value of infinity
from a stream?


[Snip discussion about C++ not supporing infinity]


Well, this is what I think I'll put into production, unless anyone can show
me any flaws in it. It seems to work fine as a float in my rudimentary
tests.

namespace jml
{
    class Float
    {
    public:
        Float( float Value = 0.0f ): Value( Value ) {}
        operator float() { return Value; }
        float Value;
    };

    std::istream& operator>>( std::istream& is, Float& mf )
    {
        if ( is >> mf.Value )
        {
            if ( mf.Value == 1.0f && is.peek() == '#' )
            {
                std::string Rest;
                is >> Rest;
                if ( Rest == "#INF" )
                    mf.Value = std::numeric_limits<float>::infinity();
            }
        }

        return is;
    }

};

I'll probably make Value private just because.

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