Give me a reason!

**julia** · 04-27-2002

can anybody explain this simple code for me.

I don't understand how the ">>" and "&" work. Thanks a lot!!

#include<stdio.h>

#define A_BYTES_SIZE 8
#define A_WORDS_SIZE 16

void main (void)
{
int ValueToConvert=256,
CurrentBitPosition=1;
unsigned int BitMask=1;

printf("The following value %d,\n",ValueToConvert);
printf("in binary form looks like:");

while (CurrentBitPosition<=A_WORDS_SIZE){
if ( (ValueToConvert>>(A_WORDS_SIZE-CurrentBitPosition) )& BitMask)
printf("1");
else
printf("0");
if( CurrentBitPosition ==A_BYTES_SIZE)
printf(" ");
CurrentBitPosition;
}
}

**Shiro** · 04-27-2002

A = A >> B

Shift the bits in A to right over B positions.

1101 >> 2 = 0011

A = A & B

Bitwise AND-operation.

0 AND 0 = 0
0 AND 1 = 0
1 AND 1 = 1

1101 & 1011 = 1001

**swoopy** · 04-28-2002

>if( CurrentBitPosition ==A_BYTES_SIZE)
>printf(" ");
>CurrentBitPosition;

And I think this should be:
CurrentBitPosition++;

as you are checking each bit for a 1 or 0, starting with the leftmost (most significant) bit.

**Lynux-Penguin** · 04-28-2002

well if it is copied directly
#include (need a space) <stdio.h>

Code:

#include <stdio.h> 

#define A_BYTES_SIZE 8 
#define A_WORDS_SIZE 16 

int main() 
{ 
	int ValueToConvert=256, 
	CurrentBitPosition=1; 
	unsigned int BitMask=1; 

	printf("The following value %d,\n",ValueToConvert); 
	printf("in binary form looks like:"); 

	while (CurrentBitPosition<=A_WORDS_SIZE){ 
		if ( (ValueToConvert>>(A_WORDS_SIZE-CurrentBitPosition) )& BitMask) 
			printf("1"); 
		else 
		printf("0"); 
		if( CurrentBitPosition ==A_BYTES_SIZE) 
			printf(" "); 
	CurrentBitPosition; 
	} 
	return 0;
}

**julia** · 04-28-2002

Thanks a lot for your explainantion, and it's of great help to me.
Swoopy , maybe you're right. I think it's a typo.

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