bitwise operators

[HelpPlease]

hello!


I want to know how you use the bitwise operators ( &, |,^, <<, >>, ~) A sample program of how they work would be helpful.
thank you!

[*pointer]

int count_ones( unsigned x ) {
    int ones;

    /* Loop as long as x has 1 bits in it */
    for( ones = 0; x != 0; x >>= 1 ) {
        /* If the lowest order bit is 1, count it */
        if( ( x & 1 ) != 0 ) {
            ones += 1;
        }
    }

    return ones;
}

This is a simple program that counts the ones in a binary number.

[Natase]

I know how these work but my explanation will probably be terrible...

As you know(?) numbers are stored as bits (1's and 0's)

e.g. 10101010 == 170

>> and << shifts this number to the right or left respectively

10101010 >> 1 (shift 1 place to the right) == 01010101

10101010 << 1 == 01010100

In both cases you lose the last digit and place a zero in the first digit.

~ reverses the number

~10101010 == 01010101
~11111111 == 00000000

& | and ^ use the following tables:

& : 1 : 0      | : 1 : 0     ^ : 1 : 0
1 : 1 : 0      1 : 1 : 1     1 : 0 : 1
0 : 0 : 0      0 : 1 : 0     0 : 1 : 0

had to edit this... looked really messy...

operator: bit == 1 : bit == 0
bit ==1 : }
bit == 0 : } results of operations

Someone correct me if I'm wrong...

[*pointer]

Looks okay to me except for your operator tables

& | and ^ use the following tables:


code:--------------------------------------------------------------------------------
& : 1 : 0 | : 1 : 0 ^ : 1 : 0
1 : 1 : 0 1 : 1 : 1 1 : 0 : 1
0 : 0 : 0 0 : 1 : 0 0 : 1 : 0
--------------------------------------------------------------------------------

Here's the correct table

& : 0 : 1    | : 0 : 1    ^ : 0 : 1
0 : 0 : 0    0 : 0 : 1    0 : 0 : 1
1 : 0 : 1    1 : 1 : 1    1 : 1 : 0

[Natase]

Identical methinks

Hehe... I take it that's a convention?