Constructors and Destructors

Are constructors called as soon as the program starts and then never used again? When are Destructors called? Thanks

A constructor is called when its class is initialized as an object. A deconstructor is called when the object is put out of play.

Quote:

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A deconstructor is called when the object is put out of play.

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Is that typically at the end of the program? Im a C programer learning C++ so Im not fluent with objects just yet.

a constructor is called when an object needs to be constructed. This could be when a temporary object is made. For instance a call by value always calls a copy constructor to copy the value to the stack.
a destructor is called immediately an object goes out of scope. This could be tiggered by somthing as simple as closing a block.
Learn about scope of variables. When a variable is made a constructor is called and when it is no longer in scope its destructor is called.

That makes more sense....Im thinking in terms of global class so I guess it would be called at the start of the program and deconstructed at the end. I definitely prefer classes over structs now.

Yeah, just to further illustrate what these guys said, here's some code that might help you.

Code:

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void foo() {
        MyClass test_class;
        //MyClass's constructor just got called because an object instance
        //of it was declared

        //MyClass's destructor will be called when the end of the function
        //comes because the object will go out of scope
}

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I don't know if you are familiar with the new and delete operators, but here's an example using them:

Code:

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void foo() {
        MyClass* test_class;
        //Constructor is NOT called here because you haven't created an
        //object of MyClass, just a pointer to an object

        test_class = new MyClass;
        //Here, constructor is called because you are creating an object
        //of MyClass with the new operator

        delete test_class;
        //Here the destructor is called because you are destroying the
        //object
}

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Hope that helps a little bit

That makes more sense....Im thinking in terms of global class so I guess it would be called at the start of the program and deconstructed at the end. I definitely prefer classes over structs now.

I dont know where that last post of mine came from...but in any case I understand now. Thanks a lot for the help.