Function does not change passed pointer C++

Question

I have my function and I am filling targetBubble there, but it is not filled after calling this function, but I know it was filled in this function because I ha

Answer 1

if you write

int b = 0;
foo(b);

int foo(int a)
{
  a = 1;
}

you do not change 'b' because a is a copy of b

if you want to change b you would need to pass the address of b

int b = 0;
foo(&b);

int foo(int *a)
{
  *a = 1;
}

same goes for pointers:

int* b = 0;
foo(b);

int foo(int* a)
{
  a = malloc(10);  // here you are just changing 
                   // what the copy of b is pointing to, 
                   // not what b is pointing to
}

so to change where b points to pass the address:

int* b = 0;
foo(&b);

int foo(int** a)
{
  *a = 1;  // here you changing what b is pointing to
}

hth