Names

• Names in C must begin with a letter or underscore (_), followed by zero or more letters, digits or underscores
  • Names beginning with an underscore are usually reserved for use by library routines
• C keywords (while, for, do, etc.) are reserved and may not be used as variable names
• Traditionally, variable names are written using lower case and preprocessor names are written using upper case
• Names can be of any length, but should be unique in the first 31 characters
  • If a name is to be visible outside a given file (a library routine, for example) the ANSI C standard only guarantees that the first 6 characters will be used and that those may even be treated in a case-insensitive manner