Need a little help in bitwise operators.

Question

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??

Answer 1

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.

Answer 2

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!

Answer 3

@David , 👏 , I better copy this post thread , it's not gonna be better than this , for the new ones