Question

The following is a small scale example of the problem I am facing. In the example below I use int pointers but in my own code I am really using a pointer to another class.

I do need/want to be able to pass multiple pointers to the same method and I do not really want to write a specific method for each pointer.
When I run the code, of course, I do not get the expected results.

I think I have narrowed down the problem but am not sure how to fix it. Since everything in C++ is pass by value, the pointers that I am passing around need to be pass by reference. I did try changing my methods to call by reference like this in the below method:

int** getIntPointer() {return &p1;} 

void initializeP1(int **&ip,int n) and void initializeP1(int **ip,int n)

But nothing seems to be working.

Does anyone have a clue how to fix this?

Thank you

#include <iostream>

using namespace std;

class Test {
  private:
    int *p1;   
    int *p2;
    int sizeP1;
    int sizeP2;   
  public:
    int** getIntPointer() {return &p1;}
    void initializeP1(int **&ip,int n){
        sizeP1=n; 
        *ip=new int[n];

        for(int i=0;i<n;i++)
            *ip[i]=i;         
    }  
    void printP1() {
        for(int i=0;i<sizeP1;i++)
            cout<<p1[i]<<" "; 
    }
};

int main() {
    Test t;
    int** p = t.getIntPointer();
    t.initializeP1(*&p,10);
    t.printP1(); 

    return 0;
}

Answer 1

This line is wrong:

*ip[i]=i;

The [] operator has higher precedence than the * operator, so that line is equivilent to this:

*(ip[i])=i;

You need to change it to this instead:

(*ip)[i]=i;