15.5 Statements

Every statement is an expression, optionally followed by a modifier, and terminated with a semicolon. The semicolon may be omitted if the statement is the final one in a block.

Execution of expressions can depend on other expressions using one of the modifiers if, unless, while, or until, for example:

expr1 if expr2 ;
expr1 until expr2 ;

The logical operators | |, & &, or ? : also allow conditional execution:

expr1 | | expr2 ;
expr1 ? expr2 : expr3 ;

Statements can be combined to form a block when enclosed in { }. block s may be used to control flow:

if (expr) block [ [ elsif (expr) block...] else block ]

unless (expr) block [ else block ]

[ label: ] while (expr) block [ continue block ]

[ label: ] until (expr) block [ continue block ]

[ label: ] for ( [ expr ] ; [ expr ] ; [ expr ] ) block

[ label: ] foreach var(dagger) (list ) block

[ label: ] block [ continue block ]

Program flow can be controlled with:

goto label

Continue execution at the specified label.

last [ label ]

Immediately exits the loop in question. Skips continue block.

next [ label ]

Starts the next iteration of the loop.

redo [ label ]

Restarts the loop block without evaluating the conditional again.

Special forms are:

do block while expr ;
do block until expr ;

which are guaranteed to perform block once before testing expr, and

do block

which effectively turns block into an expression.