ISRO CSE 2007 | Question: 15

Question

Consider the following pseudo-code

x:=1;
i:=1;
while (x <= 1000)
begin
    x:=2^x;
    i:=i+1;
end;

What is the value of i at the end of the pseudo-code?

• A. 4
• B. 5
• C. 6
• D. 7

Comments

Is it A.4

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Answer be 5

I=1         n=1

2                 2

 3                  2^2

4                      2^4

5                        2^16

Than loop terminate means i=5

Answer 1

1st time ... x = 2 and i = 2

2nd time ...x=4 and i=3

3rd time.....x=16 and i = 4

4th time ......before entering the loop value of x < 1000 ....it is 16 so it will enter the loop

and make i = 5

5th time x>1000 so while loop doesn't execute.....

SO the answer is i = 5

Comments

how we can know that the sign used “ ^ “ is for the power not a bitwise operator

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 Aashish Vishwakarma if you consider $\wedge$ symbol as a bitwise XOR operator then the while loop goes into an infinite loop. it will give $x=1,3,1,3...\infty$. so $\wedge$ is taken as power.

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Understood , Thank you sir @Hira Thakur

Answer 2

initialy	1st itr.. 1<=1000(true)	2nd itr..  2<=1000(true)	3rd itrn  ..4<=1000(true)	4th itrn   16<=1000(true)
x=1	x=2	x=4	x=16	x=>1000
i=1	i=2	i=3	i=4	i=5

then in the next iteration while loop will be false

and value of i=5.

B is the ans

Answer 3

Answer is Option B .