Santosh

• Jul 20th, 2005

 

shifting each bit left till the no of bits end

Paresh

• Sep 6th, 2005

 

foo(unsigned char *ByteField) 
{ 
int i=0,j=0; 
unsigned char *BytePos; 
short Bit; 
 
BytePos = ByteField + sizeof(ByteField); 
 
for (i=0; i { 
if (*(BytePos - i) > (char ) 0) 
{ 
for (j=0; j<8; j++) 
{ 
 
if (((*(BytePos - i)) & 1< { 
Bit = (i * 8) + j; 
printf("Bit Set %d n",Bit); 
} 
} 
} 
} 
} 
 
Should give u the bit which are set

Raks

• Oct 21st, 2005

 

#define ISBIT(pos,val) ((1<<(pos-1))&val)

void main(void)
{
 int i=0x00;
 int cnt=0;
 int pos=0;
 for(pos=1;pos<=(sizeof(i)*8);pos++)
 {
  if(ISBIT(pos,i))
  {
   cnt++;
  }
 }

 printf("Count %d",cnt);
}

prakash

• Jan 27th, 2006

 

int cnt_bits(int num) {

   int cnt = 0;

   while(num) {

       if(num % 2) cnt++;

       num /= 2;

   }

   return cnt;

}

ptusha

• Aug 17th, 2006

 

int fnCountbits(int num )
{
 int iCount = 0;
 while ( num )
 {
   num &= (num-1) ;
  iCount++;
 } 

return iCount;

}

Visitor

• Aug 23rd, 2006

 

Real smart solution to this question is to use a LookUp table.

gunturi.prabhakar

 Profile Answers by gunturi.prabhakar 

• May 30th, 2008

 

is this auestion refers to how many bits are set to 1 in a value.
if that is the question then simply convert that value into bit code....
then you can get the answer easily.....

stephen_benny

 Profile Answers by stephen_benny 

• Apr 3rd, 2010

 

As part of SSE4 instruction set available in Intel and AMD there is one instruction named POPCNT to count number of bits set to 1.

 

Furthermore, you can use it in gcc through the builtins __builtin_popcount [and ...countl and ...countll depending on the size of the argument] if you enable -msse4.2 

 

int __builtin_popcount (unsigned int)

Generates the popcntl machine instruction. 

 

int __builtin_popcountl (unsigned long)

Generates the popcntl or popcntq machine instruction, depending on the size of unsigned long. 

 

int __builtin_popcountll (unsigned long long)

Generates the popcntq machine instruction.

grvmab

 Profile Answers by grvmab 

• Oct 2nd, 2010

 

#include<stdio.h>
void main()
{
int n,r,c=0;
clrscr();
printf("Enter number:");
scanf("%d",&n);
while(n>0)
{
r=n%10;
c++;
n=n/10;
}
printf("nNumber of bits:%d",c);
getch();
}