Question

This is a follow on question to an earlier one.

I have learned some errors of my ways, but have extra questions. My objective is to have a local array in one method changed from another method without the use of any global variables.

void methodOne(){

        int myArray[10] = {0};
        int *pMyArray = myArray;
        
        methodTwo(&*pMyArray);
}

This should be declaring an array of null values and passing a reference to the second array as I was shown how to do so correctly here.

void methodTwo(int *passedPointer){
       
        int *localPointer =  passedPointer;

}

Next I’d like to change the values of myArray from methodTwo. So to change the first [0] element I would say:

*localPointer  = 1;

Is this correct?

Then to change the next element would I increment the pointer using:

localPoint++;
*localPointer = 2;

Would this change the second value in myArray? I’m not sure thats the correct way to do it is it?

TIA

Answer 1

Yes, this all looks like it should work. Generally when you’re passing an array to a function, you don’t assign to a local variable first though — you just pass the name of the array as the parameter: methoTwo(myArray);. The compiler will automatically convert the name of the array to a pointer to the beginning of the array.

Also note that you can use array-style notation on the receiving end, something like:

localpointer[0] = 1;
localpointer[1] = 2;

…is also reasonable and will accomplish the same as your

*localpointer = 1;
++localpointer;
*localpointer = 2;

For what it’s worth, another alternative would be:

*localpointer++ = 1;
*localpointer = 2;