(false - NOT (0)) is equal to 1?

Question

A test question: What is the result of (false - ~0)

Why (false - ~0) is 1? On 32 bit machine ~0 is 11....11 where there are 32 1 bits right? Then false to int conversion is 00....00 also 32 times, right? So we subtract from 32 0 32 1? Does it underflow and we get 1?

Answer 1

0 is int → ~0 is int and equal -1 → false gets promoted to int, which results in zero → your expression is calculated as (0 - (-1)) which equals 1.