Question

What I want to happen is for the pushFront(int) function to do this:

bool stack::pushFront( const int n )
{
  items[++top] = n;  // where top is the top of the stack
  return true; // only return true when the push is successful
}

items is a struct type of the object “item”. Have a look:

class stack
{
  stack(int capacity);
  ~stack(void);
  ...
  private:
    int maxSize; // is for the item stack
    int top;     // is the top of the stack
    struct item {
    int n;
    };
    item        *items;             

i’ve defined the ctor to the stack class object and dtor as follows:

stack::stack(int capacity)
{   
    items = new item[capacity];

    if ( items == NULL ) {
      throw "Cannot Allocoate Sufficient Memmory";
      exit(1); 
    }
    maxSize = capacity;
    top     = -1;
}

stack::~stack(void)
{
    delete [] items;

    items    = NULL;
    maxSize  = 0;
    top      = -1;
}

Yes the main issue for me is the items[++top] = n; statement. I’ve been trying to find ways around it like below:

bool stack::pushFront(const int n)
{
    int *a = new int[maxSize];
    a[++top] = n;

    return true;
}

But I cant drag (+) ‘a’ array out to see those actual array elements… Which is what I was hoping to happen..

What I want is for the statement items[++top] = n; to work..

Answer 1

bool stack::pushFront( const int n ) 
{
    if(top == maxSize-1)
        return false;
    items[++top].n = n;  // where top is the top of the stack
    return true; // only return true when the push is successful
}