3. Tokens and Terms

REXX expressions and instructions may contain the following items:

3.1. comment

A comment is a sequence of characters (on one or more lines) delimited by /* and */. Nested comments are also valid, as /* hello /* joe */ */

3.2. string

A string is a sequence of characters delimited by a single quote or double quote. Use two quotes to obtain one quote inside a string. A string may be specified in binary or hexadecimal if the final quote is followed by a B or X. If it followed by an H then is treated as a hexadecimal number. Some valid strings are:
1"Marmita"
2'0100 0001'b
3'He''s here'
4'2ed3'x
5'10'h (=16)

3.3. number

A number is a string of decimal digits with or without a decimal point. A number may be prefixed with a plus or minus sign, and/or written in exponential notation. Some valid numbers are:
123
212.07
3141
412.2e6
5+5
6'-3.14'

3.4. symbol

A symbol refers to any group of characters from the following selection: A-Z, a-z, 0-9, @ # $ _ . ? !

Symbols are always translated to uppercase. Variables are symbols but the first character must not be a digit 0-9 or a dot ‘.’. Each symbol may consist of up to 250 characters.

3.5. function-call

A function-call invokes an internal, external, or built-in routine with 0 to 10 argument strings. The called routine returns a character string. A function-call has the format:

function-name( [expr][,[expr]…)

function-name must be adjacent to the left parenthesis, and may be a symbol or a string.

All procedures can be called as functions or procedures. If a function is called as a procedure CALL left ‘Hello’,4 then the return string will be returned in the variable RESULT (where in this example will contain the string ‘Hell’)

copies(‘ab’,3) /* will return ‘ababab’ */