Virtual function

This is a discussion on Virtual function within the C++ Programming forums, part of the General Programming Boards category; I have a virtual function: virtual void set_num(double number = 56.00); I also have a function get_num(). In the virtual ...

  1. #1
    Microsoft. Who? MethodMan's Avatar
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    Virtual function

    I have a virtual function:

    virtual void set_num(double number = 56.00);

    I also have a function get_num().

    In the virtual function, if a value is greater than 100, I have to set it to 100.

    Code:
    set_num(double number)
    {
    	
    	if (number > 100.0)
    	{
    		number1 = 100.0; // number1 is a private instance method
    	}
    	
    }
    If I dont specify a value, I dont get the default 56.00 printed, and if I put a number over 100, it doesnt output 100.

    Thanks
    -MethodMan-

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  2. #2
    Microsoft. Who? MethodMan's Avatar
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    I fixed one problem, but another one came up.

    I have a default value of 56.00, and when I call that function with no parameter, it doesnt set the instance varialbe number1 to 56.00. How can I accomplish that?

    Thanks
    -MethodMan-

    Your Move:Life is a game, Play it; Life is a challenge, Meet it; Life is an opportunity, capture it.

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  3. #3
    Code Goddess Prelude's Avatar
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    Is this in the base class or a derived class? Can you show us something compilable that demonstrates the problem?

    -Prelude
    My best code is written with the delete key.

  4. #4
    Microsoft. Who? MethodMan's Avatar
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    This is in the base class.

    I have a function

    virtual void set_num(double number = 56.00);

    I have an instance variable number1;

    A funvtion get_num(), returns the instacne variable number1.

    So, if I use set_num(), with no argument, wanting the 56 defaulted, it wont set numbe1 to 56.00.
    -MethodMan-

    Your Move:Life is a game, Play it; Life is a challenge, Meet it; Life is an opportunity, capture it.

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  5. #5
    Banned master5001's Avatar
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    Do you have another set_num() declaration (one with no parameters). Although your compile would warn you of something like that I can't think of any other reason why you are having trouble. Also, make sure you are putting the default in the actual declaration of the class i.e.

    Code:
    class myclass {
        void set_num(double=56.0);
    };
    If you only put it where you are defining the function then the compiler won't know what to do with the default value.

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