Syntax

A function call is a term in an expression that calls a routine that carries out some procedures and returns a string. This string replaces the function call in the continuing evaluation of the expression. You can include function calls to internal and external routines in an expression anywhere that a data term (such as a string) would be valid, using the notation:


                   .-,--------------.      
                   V                |      
>>-function_name(----+------------+-+--)-----------------------><
                     '-expression-'

The function_name is a literal string or a single symbol, which is taken to be a constant.

There can be up to an implementation-defined maximum number of expressions, separated by commas, between the parentheses. In TSO/E, the implementation maximum is up to 20 expressions. These expressions are called the arguments to the function. Each argument expression may include further function calls.

Note that the left parenthesis must be adjacent to the name of the function, with no blank in between, or the construct is not recognized as a function call. (A blank operator would be assumed at this point instead.) Only a comment (which has no effect) can appear between the name and the left parenthesis.

The arguments are evaluated in turn from left to right and the resulting strings are all then passed to the function. This then runs some operation (usually dependent on the argument strings passed, though arguments are not mandatory) and eventually returns a single character string. This string is then included in the original expression just as though the entire function reference had been replaced by the name of a variable whose value is that returned data.

For example, the function SUBSTR is built-in to the language processor (see SUBSTR (Substring)) and could be used as:

N1='abcdefghijk'
Z1='Part of N1 is: 'substr(N1,2,7)
/* Sets Z1 to 'Part of N1 is: bcdefgh' */

A function may have a variable number of arguments. You need to specify only those that are required. For example, SUBSTR('ABCDEF',4) would return DEF.