The names given to variables, functions, and data types are called
identifiers. There are some restrictions upon the actual
characters that make up an identifier. An identifier name must
start with an alphabetic character ([A-Za-z]
), an underscore
character, or a dollar sign. The rest of the characters in the
name can be any combination of letters, digits, dollar signs, or
underscore characters. However, all identifiers whose name begins
with two underscore characters are reserved for internal use by the
interpreter and declarations of objects with such names should be
avoided.
Examples of valid identifiers include:
mary _3 _this_is_ok
a7e1 $44 _44$_Three
However, the following are not legal:
7abc 2e0 #xx
In fact, 2e0
actually specifies the double precision number
2.0
.
There is no limit to the maximum length of an identifier. For practical usage it is wise to limit the length of identifiers to a reasonable value.
The following identifiers are reserved by the language for use as keywords:
and andelse break case catch
continue define do else ERROR_BLOCK
exch EXIT_BLOCK finally _for for
foreach forever !if if ifnot
loop mod not or orelse
pop private public return shl
shr static struct switch __tmp
then throw try typedef USER_BLOCK0
USER_BLOCK1 USER_BLOCK2 USER_BLOCK3 USER_BLOCK4 using
variable while xor