OOPS - What is the most efficient way to count the number of bits which are set in a value?

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What is the most efficient way to count the number of bits which are set in a value?

Total Answers and Comments: 7

Last Update: May 30, 2008

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July 20, 2005 12:20:29

Santosh

RE: What is the most efficient way to count the number of bits which are set in a value?

shifting each bit left till the no of bits end

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September 06, 2005 04:55:36

Paresh

RE: What is the most efficient way to count the number of bits which are set in a value?

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

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October 21, 2005 07:10:41

Raks

RE: What is the most efficient way to count the numbe...

#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);
}

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January 27, 2006 23:57:26

prakash

RE: What is the most efficient way to count the numbe...

int cnt_bits(int num) {

int cnt = 0;

while(num) {

if(num % 2) cnt++;

num /= 2;

}

return cnt;

}

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August 17, 2006 23:58:22

ptusha

RE: What is the most efficient way to count the numbe...

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

return iCount;

}

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August 23, 2006 15:34:43

Visitor

RE: What is the most efficient way to count the numbe...

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

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May 30, 2008 15:13:46

gunturi.prabhakar

Member Since: May 2008 Contribution: 4

RE: What is the most efficient way to count the number of bits which are set in a value?

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.....

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