conversion from infix to prefix

Question

I am preparing for an exam where i couldn\'t understand the convertion of infix notation to polish notation for the below expression:

(a–b)/c*(d + e – f / g)         


        

Answer 1

This algorithm will help you for better understanding .

Step 1. Push “)” onto STACK, and add “(“ to end of the A.

Step 2. Scan A from right to left and repeat step 3 to 6 for each element of A until the STACK is empty.

Step 3. If an operand is encountered add it to B.

Step 4. If a right parenthesis is encountered push it onto STACK.

Step 5. If an operator is encountered then: a. Repeatedly pop from STACK and add to B each operator (on the top of STACK) which has same or higher precedence than the operator. b. Add operator to STACK.

Step 6. If left parenthesis is encontered then a. Repeatedly pop from the STACK and add to B (each operator on top of stack until a left parenthesis is encounterd) b. Remove the left parenthesis.

Step 7. Exit