Q. Write down an algorithm to convert an infix expression into the postfix expression.    

Ans.

Algorithm to convert infix expression to post fix expression is given as follows.

1. opstk = the empty stack;

2. while (not end of input) {

3. symb = next input character;

4. if (symb is an operand) add symb to postfix string

5. else {

6. while (!empty (opstk) and prcd (top (opstk), symb)>0){

7. topsymb = pop(opstk);

8. add topsymb to the postfix string; }/*end while*/

9. if (empty (opstk) || symb! = ')' ) push (opstk, symb); else /*pop the open parenthesis and discard it */

topsymb = pop(opstk);

} /* end else */

}/* end while */

/* output any remaining operator */

10.while (!empty (opstk)){

11. top symb = pop (opstk);

12. add topsymb to the postfix string;

} /* end while * /

/*output any remaining operator*/