C Programming - Expressions - Discussion
Discussion Forum : Expressions - Find Output of Program (Q.No. 2)
2.
Assuming, integer is 2 byte, What will be the output of the program?
#include<stdio.h>
int main()
{
printf("%x\n", -2<<2);
return 0;
}
Answer: Option
Explanation:
The integer value 2 is represented as 00000000 00000010 in binary system.
Negative numbers are represented in 2's complement method.
1's complement of 00000000 00000010 is 11111111 11111101 (Change all 0s to 1 and 1s to 0).
2's complement of 00000000 00000010 is 11111111 11111110 (Add 1 to 1's complement to obtain the 2's complement value).
Therefore, in binary we represent -2 as: 11111111 11111110.
After left shifting it by 2 bits we obtain: 11111111 11111000, and it is equal to "fff8" in hexadecimal system.
Negative numbers are represented in 2's complement method.
1's complement of 00000000 00000010 is 11111111 11111101 (Change all 0s to 1 and 1s to 0).
2's complement of 00000000 00000010 is 11111111 11111110 (Add 1 to 1's complement to obtain the 2's complement value).
Therefore, in binary we represent -2 as: 11111111 11111110.
After left shifting it by 2 bits we obtain: 11111111 11111000, and it is equal to "fff8" in hexadecimal system.
Discussion:
33 comments Page 3 of 4.
VENKAT said:
10 years ago
In above explanation why you added only two zeros please can you explain?
Nitesh Alashe said:
10 years ago
Firstly 2: 0000 0000 0000 0010.
Make complement of 2 we get -2: 1111 1111 1111 1101 (All 0's to 1 and 1's to 0).
Then add 1 in that, then it becomes +1: 1111 1111 1111 1110.
As there is << operator which is pointing towards right to left.
So add 2 zero's to right it becomes 1111 1111 1111 1000 which is FFF8.
So option C.
Make complement of 2 we get -2: 1111 1111 1111 1101 (All 0's to 1 and 1's to 0).
Then add 1 in that, then it becomes +1: 1111 1111 1111 1110.
As there is << operator which is pointing towards right to left.
So add 2 zero's to right it becomes 1111 1111 1111 1000 which is FFF8.
So option C.
Saisudha said:
1 decade ago
How is left shifting done? Can anyone please explain it?
Nani said:
1 decade ago
Why should we follow hexadecimal formats?
Mausami said:
1 decade ago
But if there is negative then shifting means appending 1's rather than 0's.
Am I right ?
Am I right ?
Vamsi reddy said:
1 decade ago
Why is it, in hexadecimal form ? please explain.
S_14 said:
1 decade ago
@Svetta, @Swati :
Explaining left shift by 2 bits:
Append two zeros on the right hand side, then write whole no before them (excluding the 2 bits at left hand side).
Why we are shifting the two bits by left?
Explaining left shift by 2 bits:
Append two zeros on the right hand side, then write whole no before them (excluding the 2 bits at left hand side).
Why we are shifting the two bits by left?
Falcon said:
1 decade ago
@Sameer
In dev-c integer is 4 byte
In dev-c integer is 4 byte
Swati said:
1 decade ago
How is shifting done ? please tell anyone.
Svetta said:
1 decade ago
How is shifting done?
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