C Proramming

Question

main()

{

unsigned int num;

int i;

scanf("%u",num);

for(i=0;i<16;i++)

printf("%d", num << i  &  1 <<15 ? 1 : 0);

}

This program calculates the binary equivalent of a number. Can anyone explain its working??

Answer 1

your program will print 16 bit binary equivalent.

let,instead of  "0 to 15" , for loop iterates from "0 to 3" to print 4 bit binary equivalent.

then working is as given below:

num=2 . binary equivalent =0010

iteration 1: i=0

2<<0 & 1<<3 means left shift 2 by 0 and 1 by 3 and then perform bitwise and(&) of both

as 2<<0=0010 and 1<<3= 1000 therefore ending both will give us 0000 therefore 0 will be printed according to condition,

iteration 2: i=1

2<<1&1<<3=0100&1000=0000, 0 will be printed

iteration 3: i=2

2<<2&1<<3= 1000&1000=1000 (non zero), 1 will be printed

iteration 4:i=3

2<<3&1<<3=0000& 1000 =0000 , zero fill be printed

therefore final result on screen  will be 0010

similarly u can analyze for 16 bit output.

LOGIC OF PROGRAM:

extract one bit from left side of binary representation of given number by left shifting and then check whether it is 1 or 0 by ending it with 1 and print the result of ending.

Comments

Got it! thank you :)