Use K& R book
There are a few problems with bosses:
1. # define NUMBER '0' why refers to find a NUMBER? ASCLL code value of 0 48, isn't it, should not be replaced with 48 his
2. # define square (x) * x x is wrong don't understand why, have said in the book of expressions to calculate twice what meaning be? Bosses to solve genuflect is begged crab crab!