Sign ~

Question

what does the sign "~" before the expression mean
https://code.sololearn.com/cY45oJv6Ef73/?ref=app

Answer 1

~ is for bitwise complement.
The ASCII value of 'c' is 99. 99*-1 = -99. ~(-99) = 98. 98 is the ASCII value of 'b' (that's the output).
To understand how ~ works, read this: https://en.m.wikipedia.org/wiki/Two%27s_complement and this: https://stackoverflow.com/questions/791328/how-does-the-bitwise-complement-operator-tilde-work