The push operation is fundamentally inserting a new element on the top of the stack. It's a core operation associated with the stack data structure, which follows the Last-In, First-Out (LIFO) principle.
Understanding the Stack and Push
A stack is a linear data structure where operations are performed only at one end, referred to as the "top" of the stack. Think of it like a stack of plates – you can only add or remove plates from the top.
- Push Operation: As defined, this action involves adding a new data element onto the current top of the stack. When you push an element, it becomes the new top element.
- Pop Operation: This is the complementary operation to push. According to the reference, deleting a data element from the top of the stack is known as pop operation.
This structure means that the last element added (pushed) is always the first element to be removed (popped).
How Push Works (Conceptual Example)
Imagine an empty stack.
- Push 'A': Stack:
[A](A is at the top) - Push 'B': Stack:
[A, B](B is now at the top) - Push 'C': Stack:
[A, B, C](C is now at the top)
In this sequence, 'C' was the last element pushed, making it the first one that would be accessible for a pop operation.
Implementing the Push Operation
The reference notes that you can perform the implementation of the stack in memory using two primary data structures:
- Stack implementation using array: A fixed-size array can be used, with an index or pointer tracking the "top" of the stack. Pushing involves placing the new element at the next available position and updating the top index. Care must be taken to avoid pushing onto a full stack (stack overflow).
- Stack implementation using linked-list: A linked list can also represent a stack. Pushing typically involves adding a new node at the beginning (head) of the list, making the new node the new "top". This implementation generally doesn't suffer from fixed-size limitations like arrays.
Both methods achieve the same logical result for the push operation: adding an element to the position designated as the top of the stack.
