$ perl -wMstrict -e 'my $s = ("111","222","aaa","bbb")' Useless use of a constant ("111") in void context at -e line 1. Useless use of a constant ("222") in void context at -e line 1. Useless use of a constant ("aaa") in void context at -e line 1. $ perl -wMstrict -e 'my $s = "111","222","aaa","bbb" ' Useless use of a constant ("222") in void context at -e line 1. Useless use of a constant ("aaa") in void context at -e line 1. Useless use of a constant ("bbb") in void context at -e line 1.