function delete dont work in the second time i activate it

Question

i have a function that contains delete in it:

void Vector::reserve(int n){
    //if there is a need to increase the size of the vector
    if (n > _size){
        int* tampArr;
        //check what the new size of the array should be
        _capacity = n + (n - _capacity) % _resizeFactor;
        tampArr = new int[_capacity];
        //put in the new array the element i have in the curr array
        for (int i = 0; i < _size; i++){
            tampArr[i] = _elements[i];
        }
        delete[] _elements;
        _elements = NULL;//this 
        //put the new array in _element
        _elements = new int[n];
        for (int i = 0; i < _size; i++){
            _elements[i] = tampArr[i];
        }
        delete[] tampArr;
    }
}

the class field is:

private:
    //Fields
    int* _elements;
    int _capacity; //Total memory allocated
    int _size; //Size of vector to access
    int _resizeFactor; // how many cells to add when need to reallocate

for some reason the first time i use the function it doesn't show any errors and work perfect but in the second time its stops in the line: "delete[] _elements;" it stops. in addition when i run this function one time it stops at the end of the object:

Vector::~Vector(){
    delete[] _elements;
}

can someone help me?

make sure that `_elements` is set to `NULL` in the constructor, otherwise `reserve` deletes some undefined memory area. to help you further we would need a [mcve] — Jean-François Fabre, Nov 17 '16 at 20:07
I hope you are aware that your final _elements array is of size n and not _capacity. — Abhishek Bansal, Nov 17 '16 at 20:19
@AbhishekBansal thank you. i hate that kind of errors, my eyes just jumped above this line every time... — Holo, Nov 17 '16 at 20:27
@YuvalPaz 1) Don't start your name with underscores. 2) Why not use `std::vector`? — PaulMcKenzie, Nov 17 '16 at 21:23
More on the above underscore comment: [What are the rules about using an underscore in a C++ identifier?](http://stackoverflow.com/questions/228783/what-are-the-rules-about-using-an-underscore-in-a-c-identifier) — user4581301, Nov 17 '16 at 21:58
@PaulMcKenzie: Those are perfectly valid symbols at class scope. Symbols starting with an underscore are only reserved at global scope. — IInspectable, Feb 13 '17 at 17:26

score -3 · Answer 1 · answered Nov 17 '16 at 20:10

-3

You don't check that _elements is valid before you delete it. Assuming you don't set _elements somewhere else, this is a major bug. Add: if(_elements) delete[] _elements; And also make sure you initialize *_elements to be null before this function is called.

answered Nov 17 '16 at 20:10

Ryan

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1
10

4

deleting a nullptr is perfectly legal and well-behaved (does nothing). – Mat Nov 17 '16 at 20:13

function delete dont work in the second time i activate it

1 Answers1