Question

While evaluating a postfix expression, when an operator is encountered, what is the correct operation to be performed?

(a) push it directly on to the stack

(b) pop 2 operands, evaluate them and push the result on to the stack

(c) pop the entire stack

(d) ignore the operator

This question is from Application of Stacks topic in section Application of Stacks of Data Structures & Algorithms I

I had been asked this question in homework.

Answer 1

Right choice is (b) pop 2 operands, evaluate them and push the result on to the stack

The explanation is: When an operator is encountered, the first two operands are popped from the stack, they are evaluated and the result is pushed into the stack.