first

OPL function to return the first element in a set.

Purpose

OPL function to return the first element in a set. For the scheduling function on interval variables, see first (scheduling).

type
int, float, string, or a tuple type

Syntax

int first({int})
float first({float})
string first({string})
<tuple type> first({<tuple type>})

Description

Returns the first element in a set. You can use this function within IBM ILOG Script statements by specifying the OPL namespace:

(Opl.xxx())

Example

The following code

{string} Days ={"Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"};

string f = first(Days);

execute
{
 writeln("first(",Days,") gives ",f);  
}

initializes f to Monday. This also indicates that sets in OPL are totally ordered according to their order of appearance in the initialization.

Result

first( {"Monday" "Tuesday" "Wednesday" "Thursday" "Friday" "Saturday" "Sunday"}) gives Monday