##
trim(string,tt/leftcharacter_set/, tt/right_character_set/);
##
##
for($var){
when($_ eq 'b'){ ...;} # means if ($var eq 'b') { ... ; last}
when($_ >'c'){...;}
} # for
##
##
my rc==0;
for(...){
if (condition1) { $rc=1; last;}
elsif(...){$rc=2; last}
}
if ($rc==0){...}
elif($rc==1){...}
elif($rc==3){...}
##
##
for ...{
when (...);
when (...);
}after{
default:
1: ...
2: ...
}