c - Significance of %x and ~

Question

int m=32
printf("%x" , ~m);

Output of this statement is ffdf and without ~ output is 20. What is the significance of %x and ~?

Answer 1

The ~ operator is bitwise negation. It will print bitwise negation of m's value. %x means that printf will output its value in hexadecimal format.

So, value 0xffdf is the negation of value 0x20 (32).

Value 32 (int bits would be):

0000 0000 0010 0000

Its bitwise negation will be:

1111 1111 1101 1111

Which makes sense since:

1111 1111 = 0xff

And:

1101 1111 = 0xdf