Question

Consider the following C code. Assume that unsigned long int type length is 64 bits.
unsigned long int fun (unsigned long int n) {
unsigned long int i, j = 0, sum = 0;
for (i = n; i > 1; i = i/2) j ++;
for (;j > 1; j = j/2) sum++;
return (sum);
}
The value returned when we call fun with the input $2^{40}$ is

• A. 40
• B. 6
• C. 4
• D. 5

Answer 1

The correct option is D 5

First for loop deal with value of 'j':
1. for (i = n; i > 1, i = i/2)
j++;
$When2=2^{40}willmake$
$j=log\left(2^{40}\right)$= 40.
Second for loop deal with value of 'sum':
Now for j = 1 loop will terminate and return sum = 5.