Double in object method not accepting fractional values?

I am having trouble with a C++ object-orientated script. When I create an object, I wish to calculate an AttributeQ based on its attributes MyAValue, MyBValue, and MyCValue.

While using the Visual 2010 debugger, I noticed that TempAttribueQ seems to always be 0 (except before it is initialized of course). Assuming Delta != 0, BVal == Maximum, and DeltaA == DeltaC, then TempAttribueQ should be 1/3 not 0.

At first I thought it was a scope problem, but the variable is defined outside the if-else statements. I have tried initializing TempAttribueQ as some outrageous number, which it keeps up until the if-else statements when it becomes 0 when it shouldn't.

This is my code...

void SetMyAttribueQ(){

    double TempAVal = MyAValue;
    double TempBVal = MyBValue;
    double TempCVal = MyCValue;

    double Minimum = min(min(TempAVal, TempBVal), TempCVal);
    double Maximum = max(max(TempAVal, TempBVal), TempCVal);
    double Delta = Maximum - Minimum;

    double DeltaA = 0;
    double DeltaB = 0;
    double DeltaC = 0;

    double TempAttribueQ = 0;

    if(Delta == 0) {
        MyAttribueQ = TempAttribueQ; // this->SetMyAttribueQ(TempAttribueQ);
    }
    else {
        DeltaA = /* (a removed equation goes here... */
        DeltaB = /* (a removed equation goes here... */
        DeltaC = /* (a removed equatio开发者_运维知识库n goes here... */

        if(AVal == Maximum)
            TempAttribueQ = (DeltaC - DeltaB);
        else if(BVal == Maximum)
            TempAttribueQ = (1/3) + (DeltaA - DeltaC);
        else
            TempAttribueQ = (2/3) + (DeltaB - DeltaA);

        MyAttribueQ = TempAttribueQ;
    }
}

What is preventing TempAttribueQ from getting a value of 1/3 or 2/3? Or, what is causing it to be set to be set to 0?

When you divide one integer by another, you get an integer result. Change either or both the constants to non-integer to fix it - C++ rules will result in the other being converted to floating point before the division takes place. All of the following will work:

• 1.0 / 3.0
• 1 / 3.0
• 1.0 / 3

An integer will get converted back to a double invisibly, which is why you weren't seeing any errors in your code.

1 is an integer and 3 is an integer so 1/3 uses integer arithmetic.

You want to use 1.0/3.0 to force double precision arithmetic.

1/3 == 0 due to integer division, which is set to TempAttribueQ.

You need to do 1./3 which will produce 0.3333333..

Try 1.0/3.0 and 2.0/3.0. 1/3 and 2/3 are 0 due to integer division.