Aim :Implement a program to evaluate a given postfix expression using stacks.

Theory

A postfix expression (Reverse Polish Notation) is a mathematical expression in which operands appear before operators. It eliminates the need for parentheses and follows a stack-based evaluation.

🔹 Steps for Evaluation:

• Scan the expression from left to right.
• Push operands (numbers) onto the stack.
• When an operator is encountered:
  • Pop two elements from the stack.
  • Apply the operator.
  • Push the result back onto the stack.
• The final result is the top element of the stack.

📌 Algorithm

1. Start scanning the postfix expression from left to right.
2. If the character is an operand, push it onto the stack.
3. If the character is an operator:
   • Pop two elements from the stack.
   • Perform the operation.
   • Push the result back into the stack.
4. Repeat until the entire expression is scanned.
5. The final result is in the stack.