GATE CSE 1989 | Question: 4-ii

Question

Compute the postfix equivalent of the following infix arithmetic expression

$a + b \ast c + d * e  \uparrow f$

where $\uparrow$ represents exponentiation. Assume normal operator precedences.

Comments

is that postfix equivalent??

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Draw the expression tree and do postorder traversal. This will give post fix expression.

Answer 1

$=a+(bc*)+(d(ef↑)*)$

$=(abc*+)+(def↑*)$

$=abc*+def↑*+$

Comments

Can also be solved by making use of Operator Stack.

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abc*def↑**+

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Hi @samir757

firstly, abc*def↑**+ is not correct. It has three ‘*’s in it but input infix expression has only 2 ‘*’s

Even if we assume it as a typo and second last char as ‘+’ getting abc*def↑*++, then its still wrong

Postfix expression abc*def↑*++ assumes ‘+’ is right associative. 

But , in C, ‘+’ is left associative

For C operator precedence table, kindly refer the following link

https://en.cppreference.com/w/c/language/operator_precedence