MACROMEDIA FLEX-FLEX ACTIONSCRIPT LANGUAGE Reference page 202

The following code loops three times and creates three new variables, called , ,
caption0 caption1
and :
caption2
for (var i = 0; i<3; i++) {
set("caption"+i, "this is caption "+i);
}
trace(caption0);
trace(caption1);
trace(caption2);
See also
var
202 Chapter 5: ActionScript Core Language Elements