Stacks on Data Structure and Algorithms related Questions and Answers

Question :   While evaluating a postfix expression, when an operator is encountered, what is the correct operation to be performed? 1. push it directly on to the stack 2. pop 2 operands, evaluate them and push the result on to the stack 3. pop the entire stack 4. ignore the operator Answer :   2 - pop 2 operands, evaluate them and push the result on to the stack