STACK
Stack is a linear data structure based on LIFO(Last In First Out) principle in which the
insertion of a new element and removal of an existing element takes place at the same end
represented as the top of the stack.
To implement the stack, it is required to maintain the pointer to the top of the stack , which is
the last element to be inserted because we can access the elements only on the top of the
stack.
LIFO(Last In First Out) Principle in Stack Data Structure:
This strategy states that the element that is inserted last will come out first. You can take a pile
of plates kept on top of each other as a real-life example. The plate which we put last is on the
top and since we remove the plate that is at the top, we can say that the plate that was put last
comes out first.
Representation of Stack Data Structure:
Stack follows LIFO (Last In First Out) Principle so the element which is pushed last is popped
first.
Shri Krishnaswamy College for Women
, Types of Stack Data Structure:
• Fixed Size Stack : As the name suggests, a fixed size stack has a fixed size and cannot
grow or shrink dynamically. If the stack is full and an attempt is made to add an element to
it, an overflow error occurs. If the stack is empty and an attempt is made to remove an
element from it, an underflow error occurs.
• Dynamic Size Stack : A dynamic size stack can grow or shrink dynamically. When the
stack is full, it automatically increases its size to accommodate the new element, and when
the stack is empty, it decreases its size. This type of stack is implemented using a linked
list, as it allows for easy resizing of the stack.
Basic Operations on Stack Data Structure:
In order to make manipulations in a stack, there are certain operations provided to us.
• push() to insert an element into the stack
• pop() to remove an element from the stack
• top() Returns the top element of the stack.
• isEmpty() returns true if stack is empty else false.
• isFull() returns true if the stack is full else false.
Push Operation in Stack Data Structure:
Adds an item to the stack. If the stack is full, then it is said to be an Overflow condition.
Algorithm for Push Operation:
• Before pushing the element to the stack, we check if the stack is full .
• If the stack is full (top == capacity-1) , then Stack Overflows and we cannot insert the
element to the stack.
• Otherwise, we increment the value of top by 1 (top = top + 1) and the new value is inserted
at top position .
• The elements can be pushed into the stack till we reach the capacity of the stack.
Pop Operation in Stack Data Structure:
Removes an item from the stack. The items are popped in the reversed order in which they are
pushed. If the stack is empty, then it is said to be an Underflow condition.
Algorithm for Pop Operation:
Shri Krishnaswamy College for Women
Stack is a linear data structure based on LIFO(Last In First Out) principle in which the
insertion of a new element and removal of an existing element takes place at the same end
represented as the top of the stack.
To implement the stack, it is required to maintain the pointer to the top of the stack , which is
the last element to be inserted because we can access the elements only on the top of the
stack.
LIFO(Last In First Out) Principle in Stack Data Structure:
This strategy states that the element that is inserted last will come out first. You can take a pile
of plates kept on top of each other as a real-life example. The plate which we put last is on the
top and since we remove the plate that is at the top, we can say that the plate that was put last
comes out first.
Representation of Stack Data Structure:
Stack follows LIFO (Last In First Out) Principle so the element which is pushed last is popped
first.
Shri Krishnaswamy College for Women
, Types of Stack Data Structure:
• Fixed Size Stack : As the name suggests, a fixed size stack has a fixed size and cannot
grow or shrink dynamically. If the stack is full and an attempt is made to add an element to
it, an overflow error occurs. If the stack is empty and an attempt is made to remove an
element from it, an underflow error occurs.
• Dynamic Size Stack : A dynamic size stack can grow or shrink dynamically. When the
stack is full, it automatically increases its size to accommodate the new element, and when
the stack is empty, it decreases its size. This type of stack is implemented using a linked
list, as it allows for easy resizing of the stack.
Basic Operations on Stack Data Structure:
In order to make manipulations in a stack, there are certain operations provided to us.
• push() to insert an element into the stack
• pop() to remove an element from the stack
• top() Returns the top element of the stack.
• isEmpty() returns true if stack is empty else false.
• isFull() returns true if the stack is full else false.
Push Operation in Stack Data Structure:
Adds an item to the stack. If the stack is full, then it is said to be an Overflow condition.
Algorithm for Push Operation:
• Before pushing the element to the stack, we check if the stack is full .
• If the stack is full (top == capacity-1) , then Stack Overflows and we cannot insert the
element to the stack.
• Otherwise, we increment the value of top by 1 (top = top + 1) and the new value is inserted
at top position .
• The elements can be pushed into the stack till we reach the capacity of the stack.
Pop Operation in Stack Data Structure:
Removes an item from the stack. The items are popped in the reversed order in which they are
pushed. If the stack is empty, then it is said to be an Underflow condition.
Algorithm for Pop Operation:
Shri Krishnaswamy College for Women
