Every stack has a size that determines how many nodes it can accommodate. Attempting to push a node in a full stack will result in a stack overflow. The program may crash due to a stack overflow.
A stack is illustrated in the given image.
stackA.push(xg) will result in a stack overflow since the stack is already full.
The stack data structure
A stack is a data structure that follows a last in, first out (LIFO) protocol. The latest node added to a stack is the node which is eligible to be removed first. If three nodes (
c) are added to a stack in this exact same order, the node
c must be removed first. The only way to remove or return the value of the node
a is by removing the nodes
Main methods of a stack data structure
The stack data structure has three main methods:
push() method adds a node to the top of the stack.
pop() method removes a node from the top of the stack.
peek() method returns the value of the top node without removing it from the stack.
Stack data structure
Stack is a data structure that supports two basic operations: pushing a new item to the top of the stack and popping a single item from the top of the stack.
In order to implement a stack using a node class, we have to store a node that is currently referencing the top of the stack and update it during the push and pop operations.
from node import Node class Stack: def __init__(self, limit=1000): self.top_item = None self.size = 0 self.limit = limit def push(self, value): if self.has_space(): item = Node(value) item.set_next_node(self.top_item) self.top_item = item self.size += 1 else: print("All out of space!") def pop(self): if self.size > 0: item_to_remove = self.top_item self.top_item = item_to_remove.get_next_node() self.size -= 1 return item_to_remove.get_value() else: print("This stack is totally empty.") def peek(self): if self.size > 0: return self.top_item.get_value() else: print("Nothing to see here!") def has_space(self): return self.limit > self.size def is_empty(self): return self.size == 0