string of bits comparison question

Dear All,

I have a string of bits 0s or 1s ,the string is 32bits but for now lets keep it simple, for example :

0100

which is stored in mysql database.

Now i want to do a search for any string in which the third bit is a 1 regardless of what the other bits are, like:

xx1x (x can be either 0 or 1)

Can somebody please help me out? I heard we can use bitwise OR for this kind of search, but i've got no clue how to use it.

Thank you very much

hello friend

you can use

$single=substr($string,2,3);
if($single=='1')
//store $single in an array.

hope this can help you.

bhoomika

hi Bhoomika

Thx for the reply.

Im not sure this will work. What i need is to know how to create the mysql query and how it will work.

SELECT bit_column_name FROM table_name WHERE bit_column_name LIKE '%1__'

in SQL % is like DOS * and is like DOS ?
% matches anything matches 1 anything...

hi tekky

thx for ur reply.

If im not wrong '%1' will match '01' or '11_' but not the third index (xx1x).

please advise,

I had 2 _'s after 1

'%1'

2 single char wildcards

note "bits" are read right to left... not left to right.... 😉

if you mean the 3rd from last bit... then you want

'1%'

reasoning behind this is bits are binary, binary 1 is

0001
2
is
0010

3
0011

8
1000

hence, bit 4 is 1, means 8, bit 1 is 1 means 1....

hi tekky,

Thank you for the clear and helpful explanation 😉

No problem 🙂 (its part of my job... so I kinda have to know that stuff)