What is the value of ~0 in C?

Question

I want to get the values of INT_MIN and INT_MAX. I\'ve tried ~0 and ~0 >> 1 since the leftmost bit is a sign bit bu

Answer 1

0 is of type int. So are ~0 and ~0 >> 1 because of int type promotion

~0 has all 1s in its bit pattern and it's -1 in 2's complement, which is the default representation of most modern implementations.

Right shift in C is implementation defined. But most implementations define >> as arithmetic shift when the type is signed and logical shift when the type is unsigned

Since ~0 is int, which is a signed type, ~0 >> 1 will be an arithmetic shift right. Hence the value is sign extended, cause the value to be all 1s

You need to do unsigned(~0) >> 1 or ~0U

There are no ways to get INT_MIN and INT_MAX portably because in C there are 3 different signed type implementations beside trap representations and padding bits. That's why standard libraries always define INT_MIN and INT_MAX directly with the values