The rules governing user-defined names are explained in Chapter 1, “Anatomy of a C Program,” and Chapter 4, “Data Types.”
You can define your own names (“identifiers”) for variables, functions, and
user-defined types. Identifiers are case sensitive. For instance, the identifier
myVariable is not the same as the identifier Myvariable. You cannot use a C keyword (see the list below) as an identifier.
An identifier can contain only the following characters:
abcdefghijklmnopqrstuvwxyz
ABCDEFGHIJKLMNOPQRSTUVWXYZ
0123456789
_ (underscore)
The first character of an identifier must be a letter or the underscore character. The first 31 characters of local identifiers are significant. The name can contain more than 31 characters, but QuickC ignores everything beyond the thirty-first character. Global identifiers are normally significant to 30 characters.