hi, i have a c program as below. Does anybody know why the output c and d always equals to 1, even the parameter of or have different values ? well, what i know to do is: eg. num = 10100001 01011010 (short num) c = 0 (unsigned char c) num or c => 01011010 (the last 8 bits of num) c is declared unsigned char, because i need to to store this value into an array of char (char len[2]). And num needs to be 2 bytes long, therefore i declare it as type short. #include #include void or(short num) { unsigned char c = 0; short d = 0 ; c = num || c; d = num || d; printf("c = num || c : %d \n", c); printf("d = num || d : %d \n", d); return; } int main(void) { or(259); return 0; } thanks a lot!! thanx WantToKnow

I suspect your confusing a logical or '||' with a bitwise or '|'.

it works!!! thanks Chris Holt. you help me a lot !!