Practice: Conditions on Characters

Five problems about characters that need a condition: what kind of character is it, and where does it sit in the alphabet?

Last week's character codes plus this week's conditions are all they need:

• Is it a lowercase letter? is c >= 'a' && c <= 'z'; the same with 'A' and 'Z' for uppercase, '0' and '9' for digits.
• c - 'a' is the position of a lowercase letter (0 for 'a'), and char('a' + k) is the letter at position k.
• Upper and lower case are 32 apart: char(c - 32) and char(c + 32).
• Watch the ends of the alphabet: the letter after 'z' and the one before 'a' need a condition of their own.