![PSEUDO CODE IN C
Void push() {
int item;
printf(“Enter item to push”);
scanf(“%d”.&item);
if(top == max – 1) { // overflow condition
printf(“Stack overflow”);
}
else {
top = top + 1;
stack[top] = item;
}
}](https://image.slidesharecdn.com/stack-210706080312/85/DATA-STRUCTURE-STACK-8-320.jpg)
![PSEUDO CODE IN C
Void pop () {
if(top == -1)
printf(“Stack underflow”);
else {
printf(“The deleted item is %d”,stack[top]);
top--;
}
}](https://image.slidesharecdn.com/stack-210706080312/85/DATA-STRUCTURE-STACK-11-320.jpg)
DATA STRUCTURE - STACK
- 1. INTRODUCTION What is Stack? Stack Representation ADT specification of Stack Operations on Stack Stack Overflow and Stack Underflow Implementing of Stack Prefix, Postfix, Infix Notation Polish Notation Precedence and Priority Applications
- 2. WHAT IS STACK?? Stores a set of elements in a particular order. Stack is like a container of memory. Stack principle- LAST IN FIRST OUT(LIFO) Examples:-
- 3. LAST IN FIRST OUT
- 5. ADT SPCIFICATIONS OF STACK Operations: Make Empty Boolean Is Empty Boolean Is Full Push (Item Type new Item) Pop (Item Type& item) (or pop and top)
- 6. TOP A list with the restriction that insertion and deletion can be performed only from one end is called top. If stack is empty, then top is at -1 position. If stack is not empty, then top is at last position(n-1).
- 7. PUSH OPERATION Stack is empty, top is at -1 position. Function: Adds new Item to the top of the stack. Preconditions: Stack has been initialized and is not full. Post conditions: new Item is at the top of the stack.
- 8. PSEUDO CODE IN C Void push() { int item; printf(“Enter item to push”); scanf(“%d”.&item); if(top == max – 1) { // overflow condition printf(“Stack overflow”); } else { top = top + 1; stack[top] = item; } }
- 10. POP OPERATION Stack is not empty, then top is at last position (n-1). Removes top Item from stack and returns it in item. Always done on the top of stack The top most element is deleted first Preconditions: Stack has been initialized and is not empty. Post conditions: Top element has been removed from stack and item is a copy of the removed element.
- 11. PSEUDO CODE IN C Void pop () { if(top == -1) printf(“Stack underflow”); else { printf(“The deleted item is %d”,stack[top]); top--; } }
- 12. POP OPERATION
- 13. STACK OVERFLOW The condition resulting from trying to push an element onto a full stack. Top is at last position(n-1).
- 14. STACK UNDERFLOW The condition resulting from trying to pop an empty stack. Top is at -1 position.
- 15. IMPLEMENTING OF STACK Basics two choices:- Array Linked list 1) Array:- Array is quick, but limited in size.
- 16. IMPLEMENTING OF STACK 2) Linked list:- Linked List requires overhead to allocate, link, unlink, and deallocate, but is not limited in size
- 17. INFIX EXPRESSION Operator is used in between operands. Example:-
- 18. POSTFIX EXPRESSION Operator is used after operands. Example:-
- 19. PREFIX EXPRESSION Operator is used before operands. Example:-
- 20. POLISH NOTATION Prefix notation requires that all operators precede the two operands that they work on. Postfix notation requires that its operators come after the corresponding operands.
- 22. INFIX TO POSTFIX The infix string from left to right. Initialize an empty stack. Character is an operand, add it to the Postfix string. If the stack is empty, push the character is an operator to stack stack is not empty, compare the precedence of the character with the element on top of the stack.
- 23. EXAMPLE OF INFIX TO POSTFIX
- 24. INFIX TO PREFIX Reverse given prefix expression. Conversion same as infix to postfix expression. Reverse the expression.
- 25. EXAMPLE OF INFIX TO PREFIX
- 26. EVALUATION OF POSTFIX Create a stack to store operands (or values). If the element is a number, push it into the stack. If the element is a operator, pop operands for the operator from stack. Evaluate the operator and push the result back to the stack when the expression is ended, the number in the stack is the final answer.
- 27. EXAMPLE OF EVALUATION OF POSTFIX
- 28. EVALUATION OF PREFIX Accept a prefix string from the user. The string from the right one character at a time. If it is an operand, push it in stack. If it is an operator, pop and perform the operation, specified by the operator. Push the result in the stack. The number in stack is final answer.
- 29. EXAMPLE OF EVALUATION OF PREFIX
- 30. APPLICATIONS Parsing Recursive Function Calling Function Expression Evaluation Expression Conversion Infix to Postfix Infix to Prefix Postfix to Infix Prefix to Infix