if (EXPR) BLOCK
if (EXPR) BLOCK else BLOCK
if (EXPR) BLOCK elsif (EXPR) BLOCK ... else BLOCK
+ unless (EXPR) BLOCK
+ unless (EXPR) BLOCK else BLOCK
LABEL while (EXPR) BLOCK
LABEL while (EXPR) BLOCK continue BLOCK
LABEL until (EXPR) BLOCK
The C<if> statement is straightforward. Because BLOCKs are always
bounded by curly brackets, there is never any ambiguity about which
C<if> an C<else> goes with. If you use C<unless> in place of C<if>,
-the sense of the test is reversed.
+the sense of the test is reversed. In Perl even C<unless> followed
+by C<else> is valid.
The C<while> statement executes the block as long as the expression is
L<true|/"Truth and Falsehood">.