functions method of operation

[Daniel A]

Hi volks,

could anyone tell me how do these functions exactly work?

void setmax()
{

unsigned l=-1;
if(!max)
while (max++, l >>=1)
;
}


and



void printbyte()

int i;

while (i--) printf("%c", byte_ & 1U<<i ? '1':'0');

puts("");

}

I could not understand the bolded commands :(
Is there any other alternatives how to write this code in a better (easier) way?

Thank you in avance!

Dan

[jpeg]

those are while loops. They keep going until whatever is in parenthesis evaluates to false (zero).

For instance in the second loop, it decrements i by 1 every time and prints the byte. Thus this loop will terminate when i==0 if i is initially 100, then the loop will go 100 times and then move on to the next piece of code.

[Daniel A]

Thanks!!! But what I really did not understand is what do these commands in the above listed examples do? what do they mean?

l >>=1 ?

and

byte & 1U <<i ?


Thanks!!

[jsmith]

l >>= 1; is equivalent to l = l >> 1; which
is a bit shift right 1 bit (ie, equivalent to integer division by 2)

byte & 1U << i is shifting the integer value 1 left i
bits and then bitwise ANDing the result with byte.

And the comma in the first while loop is evil.