How to assign pointer of an "array of object" (C++)

Question

I am a beginner in C++ that confused over dynamic array. I found a way to do it in this site, but I can't seem to make it work for "array of object" in an object. It always break when I read the Rec variable.

This is the class definition:

class AlcXIO {
private:
    AlcX_IO_Record* Rec[1];
    int _Count;
public: 
    int count();
    void Init(CL_DisplayWindow window);
    void AddInput(int IO_ID);
    AlcX_IO_Record* GetRec(int RecID);
    void on_input_down(const CL_InputEvent &key, const CL_InputState &state);
    void on_input_up(const CL_InputEvent &key, const CL_InputState &state);
};

The AddInput() function:

void AlcXIO::AddInput(int IO_ID) {
    size_t newSize = this->_Count +1;
    AlcX_IO_Record* newArr = new AlcX_IO_Record[newSize];

    memcpy( newArr, Rec, _Count * sizeof(AlcX_IO_Record) );

    _Count = newSize;
    delete [] Rec;
    Rec[0] = newArr;
}

I aware that I'm probably wrong on: Rec[0] = newArr

But changing it to Rec = newArr gives me an error: "expression must be a modifiable lvalue"

Any solution is welcome, thank you.

Niels Keurentjes · Accepted Answer · 2013-05-19 13:50:41Z

1

Remove the [1] from the declaration, you're using it as a pointer, not an array of pointers as it is declared now. The error stems from trying to overwrite the fact that you declared it as an array - the type cannot be changed programmatically at runtime, even though it's technically compatible.

answered May 19, 2013 at 13:50

Niels Keurentjes

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3 Comments

Hajime Saki Over a year ago

it give me "error C2229: class 'AlcXIO' has an illegal zero-sized array" :( EDIT: changing it to AlcX_IO_Record* Rec; gives me another error "error C2100: illegal indirection"

Niels Keurentjes Over a year ago

You removed only the 1, remove the square brackets as well.

Hajime Saki Over a year ago

changing it to AlcX_IO_Record* Rec; gives me another error "error C2100: illegal indirection" on Rec = newArr;

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