how to get bit by bit data from a integer value in c?

Question

i want to extract bits of a decimal no.

for example 7 has a binary 0111 and i want to get 0 1 1 1 all bits stored in bool how can i do so?

OK loop is not a good option can do some this else to this?

Answer 1

If you want the k-th bit of n, then do

(n & ( 1 << k )) >> k

Here we create a mask, apply the mask to n, and then right shift the masked value to get just the bit we want. We could write it out more fully as:

    int mask =  1 << k;
    int masked_n = n & mask;
    int thebit = masked_n >> k;

You can read more about bit-masking here: http://en.wikipedia.org/wiki/Mask_(computing)

Here is a program:

#include <stdio.h>
#include <stdlib.h>

int *get_bits(int n, int bitswanted){
  int *bits = malloc(sizeof(int) * bitswanted);

  int k;
  for(k=0; k<bitswanted; k++){
    int mask =  1 << k;
    int masked_n = n & mask;
    int thebit = masked_n >> k;
    bits[k] = thebit;
  }

  return bits;
}

int main(){
  int n=7;

  int  bitswanted = 5;

  int *bits = get_bits(n, bitswanted);

  printf("%d = ", n);

  int i;
  for(i=bitswanted-1; i>=0;i--){
    printf("%d ", bits[i]);
  }

  printf("\n");
}

Answer 2

http://www.daniweb.com/code/snippet216349.html#

Answer 3

Here's one way to do it—there are many others:

bool b[4];
int v = 7;  // number to dissect

for (int j = 0;  j < 4;  ++j)
   b [j] =  0 != (v & (1 << j));

Answer 4

here's a very simple way to do it;

int main() {

int s=7,l=1;
vector <bool> v;
v.clear();
while(l<=4)
{
    v.push_back(s%2);
    s/=2;
    l++;
}
for(l=(v.size()-1);l>=0;l--)
{
    cout<<v[l]<<" ";
}

return 0; }