LISTLEN

LISTLEN

Reports the length of an SCL list

Category: List

Syntax
Details
Example
See Also

Syntax

n=LISTLEN(list-id );

n

contains either the length of an SCL list or status information:

>0	the length of a non-empty list
0	the list is empty
-1	the list identifier is invalid.

Type: Numeric

list-id

is the identifier of the list whose length is being queried, or any other number.

Type: Numeric or List

Details

The length of a list is the number of items in the list, excluding the contents of sublists. Because LISTLEN returns -1 if list-id is an invalid list identifier, you can use LISTLEN to determine whether a list exists. For example:

listid=getniteml(envlist('G'),'MYLIST');
invalid=(listlen(listid)=-1);
if invalid then
do;
   put 'MYLIST in the global environment has been deleted.';
   stop;
end;

Example

Create the empty list LISTA, and then insert LISTA into a copy of itself, LISTB. The lengths of the two lists are then computed and are stored in the variables LEN_A and LEN_B.

lista=makelist();
listb=copylist(lista);
listb=insertl(listb,lista);
len_a=listlen(lista);
len_b=listlen(listb);
_msg_='The length of LISTA is '||len_a||' and '||
      'the length of LISTB is '||len_b;

This example shows that the length of LISTA is 0, whereas the length of LISTB is 1.

See Also

MAKELIST

MAKENLIST

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