+ 2

Need a little help in bitwise operators.

What does the following statement do? x=x|1<<n; Can anyone explain? Answer to this question is Sets (n+1)th bit of x why??? how??

16th Jan 2018, 4:59 AM
Ayush walia
Ayush walia - avatar
3 odpowiedzi
+ 12
It's value depends on x and n. Precedence states it executes as follows: x=(x|(1<<n)); so 1 is left shifted n bits, the result is ored with x, which is finally stored in x.
16th Jan 2018, 1:44 AM
John Wells
John Wells - avatar
+ 15
Expanding on what John said, the expression shifts the positions of the binary bits n times to the left. Using the reference below we see the first five binary bit positions read right to left: 16 | 8 | 4 | 2 | 1 Note the equivalent integer to binary conversions below: 1 => 00001 [ 0 + 0 + 0 + 0 + 1 ] 2 => 00010 [ 0 + 0 + 0 + 2 + 0 ] 3 => 00011 [ 0 + 0 + 0 + 2 + 1 ] 4 => 00100 [ 0 + 0 + 4 + 0 + 0 ] 5 => 00101 [ 0 + 0 + 4 + 0 + 1 ] 6 => 00110 [ 0 + 0 + 4 + 2 + 0 ] 7 => 00111 [ 0 + 0 + 4 + 2 + 1 ] 8 => 01000 [ 0 + 8 + 0 + 0 + 0 ] 9 => 01001 [ 0 + 8 + 0 + 0 + 1 ] 10 => 01010 [ 0 + 8 + 0 + 2 + 0 ] 11 => 01011 [ 0 + 8 + 0 + 2 + 1 ] 12 => 01100 [ 0 + 8 + 4 + 0 + 0 ] Shifting bits involve moving the 1's from current bit positions by the specified number in the specified direction. Examples: ------------------------------------------------- Shifting 1 bit to the left. ------------------------------------------------- 1) 1 << 1 00001 => 00010 1 => 2 2) 2 << 1 00010 => 00100 2 => 4 3) 3 << 1 00100 => 01000 3 => 8 4) 4 << 1 01000 => 10000 4 => 16 ------------------------------------------------- Shifting 2 bits to the left. ------------------------------------------------- 5) 1 << 2 00001 => 00100 1 => 4 6) 2 << 2 00010 => 01000 2 => 8 7) 3 << 2 00011 => 01100 3 => 12 8) 4 << 2 00100 => 10000 4 => 16 ------------------------------------------------- Shifting 3 bits to the left. ------------------------------------------------- 9) 1 << 3 00001 => 01000 1 => 8 10) 2 << 3 00010 => 10000 2 => 16 I hope this makes sense. Cheers!
16th Jan 2018, 5:39 AM
David Carroll
David Carroll - avatar
+ 4
@David , 👏 , I better copy this post thread , it's not gonna be better than this , for the new ones
14th Feb 2018, 3:29 AM
Morpheus
Morpheus - avatar