Engineering Questions with Answers - Multiple Choice Questions

# Infix to Postfix Conversion Multiple Choice MCQ

1 - Question

When an operand is read, which of the following is done?
a) It is placed on to the output
b) It is placed in operator stack
c) It is ignored
d) Operator stack is emptied

Explanation: While converting an infix expression to a postfix expression, when an operand is read, it is placed on to the output. When an operator is read, it is placed in the operator stack.

2 - Question

What should be done when a left parenthesis ‘(‘ is encountered?
a) It is ignored
b) It is placed in the output
c) It is placed in the operator stack
d) The contents of the operator stack is emptied

Explanation: When a left parenthesis is encountered, it is placed on to the operator stack. When the corresponding right parenthesis is encountered, the stack is popped until the left parenthesis and remove both the parenthesis.

3 - Question

Which of the following is an infix expression?
a) (a+b)*(c+d)
b) ab+c*
c) +ab
d) abc+*

Explanation: (a+b)*(c+d) is an infix expression. +ab is a prefix expression and ab+c* is a postfix expression.

4 - Question

What is the time complexity of an infix to postfix conversion algorithm?
a) O(N log N)
b) O(N)
c) O(N2)
d) O(M log N)

Explanation: The time complexity of an infix to postfix expression conversion algorithm is mathematically found to be O(N).

5 - Question

What is the postfix expression for the corresponding infix expression?

a+b*c+(d*e)
a) abc*+de*+
b) abc+*de*+
c) a+bc*de+*
d) abc*+(de)*+

Explanation: Using the infix to postfix expression conversion algorithm, the corresponding postfix expression is found to be abc*+de*+.

6 - Question

Parentheses are simply ignored in the conversion of infix to postfix expression.
a) True
b) False

Explanation: When a parenthesis is encountered, it is placed on the operator stack. When the corresponding parenthesis is encountered, the stack is popped until the other parenthesis is reached and they are discarded.

7 - Question

It is easier for a computer to process a postfix expression than an infix expression.
a) True
b) False

Explanation: Computers can easily process a postfix expression because a postfix expression keeps track of precedence of operators.

8 - Question

What is the postfix expression for the infix expression?

`a-b-c`

a) -ab-c
b) ab – c –
c) – -abc
d) -ab-c

Explanation: The corresponding postfix expression for the given infix expression is found to be ab-c- and not abc- -.

9 - Question

What is the postfix expression for the following infix expression?

a/b^c-d
a) abc^/d-
b) ab/cd^-
c) ab/^cd-
d) abcd^/-

Explanation: Using the infix to postfix conversion algorithm, the corresponding postfix expression for the infix expression is found to be abc^/d-.

10 - Question

Which of the following statement is incorrect with respect to infix to postfix conversion algorithm?
a) operand is always placed in the output
b) operator is placed in the stack when the stack operator has lower precedence
c) parenthesis are included in the output
d) higher and equal priority operators follow the same condition

Explanation: Parentheses are not included in the output. They are placed in the operator stack and then discarded.

11 - Question

In infix to postfix conversion algorithm, the operators are associated from?
a) right to left
b) left to right
c) centre to left
d) centre to right

Explanation: In infix, prefix and postfix expressions, the operators are associated from left to right and not right to left.

12 - Question

What is the corresponding postfix expression for the given infix expression?

a*(b+c)/d
a) ab*+cd/
b) ab+*cd/
c) abc*+/d
d) abc+*d/

Explanation: Using the infix to postfix conversion algorithm, the corresponding postfix expression is obtained as abc+*d/.

13 - Question

What is the corresponding postfix expression for the given infix expression?

a+(b*c(d/e^f)*g)*h)
a) ab*cdef/^*g-h+
b) abcdef^/*g*h*+
c) abcd*^ed/g*-h*+
d) abc*de^fg/*-*h+

Explanation: Using the infix to postfix expression conversion algorithm using stack, the corresponding postfix expression is found to be abcdef^/*g*h*+.

14 - Question

What is the correct postfix expression for the following expression?

a+b*(c^d-e)^(f+g*h)-i
a) abc^de-fg+*^*+i-
b) abcde^-fg*+*^h*+i-
c) abcd^e-fgh*+^*+i-
d) ab^-dc*+ef^gh*+i-

Explanation: The postfix expression for the given infix expression is found to be abcd^e-fgh*+^*+i- when we use infix to postfix conversion algorithm.

15 - Question

From the given Expression tree, identify the correct postfix expression from the list of options.

a) ab*cd*+
b) ab*cd-+
c) abcd-*+
d) ab*+cd-