CDE

Task/Empty-string/Perl/empty-string-2.pl

@@ -0,0 +1,14 @@
+$s = "";
+if ($s) { ... }  # false
+
+# to tell if a string is false because it's empty, or it's plain not there (undefined)
+$s = undef;
+if (defined $s) { ... } # false; would be true on ""
+
+# though, perl implicitly converts between strings and numbers, so this is also false
+$s = "0";
+if ($s) { ... } # false; also false on "000", "0.0", "\x0", "0 with text", etc
+
+# but a string that converts to number 0 is not always false, though:
+$s = "0 but true";
+if ($s) { ... }  # it's true! black magic!