Comparison of 2 double values

[OneEyeMan]

Hi, ALL,
Today I got stumped by very interesting situation.
I have std::vector of players and each player have its own value. The value is of the type double, but the original value are of the "XX.00".
Now what I'm trying to do is to insert a player into this vector. For that I need to find a place and to find a place I need to compare player value.

So lets say I have a player in the vector whose value is 24.00 and I am trying to insert a player whose value is 25.00. To my surprise MSVC 2010 tells me that:

24.0000000000000 == 25.00000000000

I do aware that comparing double type is not going to work like this, but I would expect not to have such big of a difference. ;-)

Can someone please explain why this comparison is true and how to eliminate such thing?

Thank you.

[2kaud]

It would help to advise if you posted the code you use.

[Igor Vartanov]

#include <stdio.h>

int main()
{
    if (24.0000000000000 == 25.00000000000)
        printf("24.0000000000000 == 25.00000000000");
    else
        printf("24.0000000000000 != 25.00000000000");

    return 0;
}

J:\Temp\30>cl 30.cpp
Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 16.00.40219.01 for 80x86
Copyright (C) Microsoft Corporation.  All rights reserved.

30.cpp
Microsoft (R) Incremental Linker Version 10.00.40219.01
Copyright (C) Microsoft Corporation.  All rights reserved.

/out:30.exe
30.obj

J:\Temp\30>30.exe

24.0000000000000 != 25.00000000000

[GCDEF]

If I had to guess, I'd say you're statement looks more like this

if(24.0000000000000 = 25.00000000000)

Whatever it is, the problem is in your code.