Postfix evaluation using stack algorithm with example

Postfix evaluation:

Algorithm:

1.       Scan the postfix expression P from the left to right.

2.       Initialize an empty stack or NULL stack.

3.       Repeat step 4 and 5 until all characters in P are scanned.

4.       If the scanned character is operator push it to the stack.

5.       If the scanned character is an operand then à

a.       Remove top two elements from the stack

b.       Evaluate two removes elements result using the scanned operand and push the result to the stack.

6.       Finally the result of the stack is the evaluation of the postfix expression.

Example:

 Say the postfix expression is : P = 562 +* 124/-

Scanned Character	Stack
5 6 2 + * 12 4 / -	5 56 562 58 40 4012 40124 403 37

So the result of the postfix evaluation is: 37 which is the top element of the stack now





If you face any problem in this example, please comment below.