C Programming - Bitwise Operators

Exercise :: Bitwise Operators - Point Out Correct Statements

1.

Which of the following statements are correct about the program?

#include<stdio.h>

int main()
{
unsigned int num;
int i;
scanf("%u", &num);
for(i=0; i<16; i++)
{
printf("%d", (num<<i & 1<<15)?1:0);
}
return 0;
}

 A. It prints all even bits from num B. It prints all odd bits from num C. It prints binary equivalent num D. Error

Explanation:

If we give input 4, it will print 00000000 00000100 ;

If we give input 3, it will print 00000000 00000011 ;

If we give input 511, it will print 00000001 11111111 ;

2.

Which of the following statements are correct about the program?

#include<stdio.h>

int main()
{
unsigned int num;
int c=0;
scanf("%u", &num);
for(;num;num>>=1)
{
if(num & 1)
c++;
}
printf("%d", c);
return 0;
}

 A. It counts the number of bits that are ON (1) in the number num. B. It counts the number of bits that are OFF (0) in the number num. C. It sets all bits in the number num to 1 D. Error

Explanation:

If we give input 4, it will print 1.
Binary-4 == 00000000 00000100 ; Total number of bits = 1.

If we give input 3, it will print 2.
Binary-3 == 00000000 00000011 ; Total number of bits = 2.

If we give input 511, it will print 9.
Binary-511 == 00000001 11111111 ; Total number of bits = 9.

3.

Which of the following statements are correct about the program?

#include<stdio.h>
char *fun(unsigned int num, int base);

int main()
{
char *s;
s=fun(128, 2);
s=fun(128, 16);
printf("%s\n",s);
return 0;
}
char *fun(unsigned int num, int base)
{
static char buff;
char *ptr = &buff[sizeof(buff)-1];
*ptr = '\0';
do
{
*--ptr = "0123456789abcdef"[num %base];
num /=base;
}while(num!=0);
return ptr;
}

 A. It converts a number to a given base. B. It converts a number to its equivalent binary. C. It converts a number to its equivalent hexadecimal. D. It converts a number to its equivalent octal.

Explanation:

No answer description available for this question. Let us discuss.

4.

Which of the following statements are correct about the program?

#include<stdio.h>

int main()
{
unsigned int m[] = {0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80};
unsigned char n, i;
scanf("%d", &n);
for(i=0; i<=7; i++)
{
if(n & m[i])
printf("yes");
}
return 0;
}

 A. It will put OFF all bits that are ON in the number n B. It will test whether the individual bits of n are ON or OFF C. It will put ON all bits that are OFF in the number n D. It will report compilation errors in the if statement.