Store binary values in an array in C

Question

I wish to store some binary values in an array in C. How it can be done and how can i access any bit of a binary number.

Plz let me know if i i am unclear in posting the doubt.

What do you mean by "binary values"? Do you mean boolean values, i.e. flags? — Oliver Charlesworth, Aug 04 '11 at 15:07
possible duplicate of [how to get bit by bit data from a integer value in c?](http://stackoverflow.com/questions/2249731/how-to-get-bit-by-bit-data-from-a-integer-value-in-c) — Oliver Charlesworth, Aug 04 '11 at 15:07
I mean i require the binary representation of all the decimal number user enters. I need this for taking some bitwise operations — Prashant Singh, Aug 04 '11 at 15:08
Why do you want to store them in binary format and not in int(s) ? You can easily create a function that creates a char* containing the binary representation of each int — Ioan Paul Pirau, Aug 04 '11 at 15:16

score 3 · Accepted Answer · answered Aug 04 '11 at 15:09

3

Store your values in a normal array and write a simple function that would pick proper element and state of its bit, something like

int get_bit_from_array( unsigned char *A, int element, int bit ) {
    return A[element] &  ( 1 << bit ) ;                 
}

or even

int get_bit_from_array( unsigned char *A, int bit_absolute) {
    int element = bit_absolute / 8;
    int bit = bit_absolute % 8;
    return A[element] &  ( 1 << bit ) ;                 
}

answered Aug 04 '11 at 15:09

Jakub M.

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hmm..thats d final solution. But is there no other alternatives, because i need to make several such calls in my program – Prashant Singh Aug 04 '11 at 15:11
I am sure sure CPU will manage :) – Jakub M. Aug 04 '11 at 15:13
Can u plz explain the above code ?? – Prashant Singh Aug 04 '11 at 15:16
what does unsigned char *A, int bit_absolute represent above ?? – Prashant Singh Aug 04 '11 at 15:19
You'd probably want to shift the result right by `bit` to finish it (after all you are asking for a bit value, not a masked bit). – Chris Eberle Aug 04 '11 at 23:40
@Chris: for boolean operations it does not matter – Jakub M. Aug 05 '11 at 06:04
Yes but if I said, "get me the value of the 5th bit", and you returned 16 that would be pretty confusing (if I were expecting a 0 or 1). – Chris Eberle Aug 05 '11 at 06:14

Store binary values in an array in C

1 Answers1