A variable that is read-only after assignment at run-time?

Question

Fairly new programmer here, and an advance apology for silly questions.

I have an int variable in a program that I use to determine what the lengths of my a

Answer 1

C++ doesn't have a built-in solution for this, but if you really want to make sure that your int is only assigned once, you can build your own special int class:

class MyConstInt
{
public: 
    MyConstInt(): assigned(false) {}
    MyConstInt& operator=(int v)
    {
        assert(!assigned); 
        value = v; 
        assigned = true; 
        return *this; 
    }   
    operator int() const 
    { 
        assert(assigned); 
        return value; 
    }
private: 
    int value; 
    bool assigned; 
}; 


MyConstInt mi; 
//  int i = mi;         //  assertion failure; mi has no value yet
mi = 42; 
//  mi = 43;        //  assertion failure; mi already has a value
int* array = new int[mi];