Constructor to specify zero-initialization of all builtin members?

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庸人自扰
庸人自扰 2020-12-06 07:53

Is there a simpler way for a class\'s constructor to specify that all members of built-in type should be zero-initialized?

This code snippet came up in another pos

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  •  小蘑菇
    小蘑菇 (楼主)
    2020-12-06 08:53

    You can use a subobject to initialize en masse. A member works, but then you need to qualify all access. So inheritance is better:

    struct MoneyData
    {
        double amountP, amountG, totalChange;
        int twenty, ten, five, one, change;
        int quarter, dime, nickel, penny;
    };
    
    struct Money : MoneyData
    {
        void foo();
        Money() : MoneyData() {} /* value initialize the base subobject */
    };
    

    Demonstration (placement new is used to make sure the memory is non-zero before object creation): http://ideone.com/P1nxN6

    Contrast with a slight variation on the code in the question: http://ideone.com/n4lOdj

    In both of the above demos, double members are removed to avoid possible invalid/NaN encodings.

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