How structs are initialized.
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Thread: How structs are initialized.

  1. #1
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    How structs are initialized.

    I have a struct.

    Code:
    struct Thing{
        int value;
        char title;
    }
    Is there a way i can make default values for the struct. So when I make one of the structures they initialize to the default values.

    Code:
    Thing myThing;
    
    cout<< myThing.value<<endl;
    So when i cout the value member it would print a default value.

  2. #2
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    Re: How structs are initialized.

    Provide a default constructor, e.g.,
    Code:
    struct Thing {
        Thing() : value(123), title('a') {}
    
        int value;
        char title;
    };
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  3. #3
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    Re: How structs are initialized.

    Excellent. This is exactly what i was looking for. My reference book does not mention the constructor use at all. Thanks

  4. #4
    Lindley is offline Elite Member Power Poster
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    Re: How structs are initialized.

    Then either it's a "C" book, or it's one of those that finds it convenient to treat structs and classes differently even though they're almost the same thing. I guarantee it'll talk about constructors when you get to classes....

  5. #5
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    Re: How structs are initialized.

    The book is a C++ book. Although it does talk about constructor use in classes they are not mentioned in the "structured data" chapter which is where structs are introduced. I found it very weird that the book did not mention anything about setting "default" values for structs. So i had to ask about it.

  6. #6
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    Re: How structs are initialized.

    structs and classes are essentially the same thing. The only difference between them is default member/inheritance is public for structs and private for classes.
    Code:
    class A {};
    class B : A // private inheritance
    {
       int b; // private
    };
    
    struct C {};
    struct D : C // public inheritance
    {
       int d; // public
    };
    Other than that there is afaik no differences between structs and classes.
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  7. #7
    Lindley is offline Elite Member Power Poster
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    Re: How structs are initialized.

    FYI, for plain-old-data types at least (not sure about others), you can do something like
    Code:
    struct mystruct
    {
        const char *str;
        int i;
        double d;
    };
    
    int main()
    {
        mystruct s = {"hello", 5, 10.0};
    }

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