Page 504 - Computer science 868 Class 12
P. 504

Let us evaluate the same with the following examples.
                1.  Convert the following Infix expression to its postfix form.                               [ISC 2010]
                    (A + B) / (C * (D + E))
                a.  Stack method

              Ans.     Scanned symbol                          Stack                        Postfix expression
                     Left parenthesis (   (
                     pushed to stack

                     A operand sent       (                                                        A
                     to output
                     + operator           +                                                        A
                     pushed to stack      (


                     B operand sent       +                                                       A B
                     to output            (

                     Right                )    Closing bracket encountered. All the operators till

                     parenthesis )        +    opening parenthesis popped and appended to the    A B +
                     pushed to stack      (    postfix expression. Stack empty . Brackets discarded

                     / operator           /                                                      A B +
                     pushed to stack

                     Left parenthesis (   (                                                      A B +
                     (pushed to stack     /

                     Operand C            (                                                      A B + C

                     appended with        /
                     postfix
                     expression

                     Operator * is        *                                                      A B + C
                     pushed to stack      (
                                          /

                     Left parenthesis (   (                                                      A B + C
                     pushed to            *

                     stack                (
                                          /
                     Operand D            (                                                     A B + C D
                     appended with        *

                     postfix              (
                     expression           /





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