15.2 Blocks

A block permits multiple statements to be written in contexts where a single
statement is allowed.
block:
{ statement-listopt }
A block consists of an optional statement-list (§15.2.1), enclosed in
braces. If the statement list is omitted,
the block is said to be empty.
A block may contain declaration statements (§15.5). The scope of a local
variable or constant declared in a
block is the block.
Within a block, the meaning of a name used in an expression context must
always be the same (§14.5.2.1).
A block is executed as follows:
? If the block is empty, control is transferred to the end point of the
block.
? If the block is not empty, control is transferred to the statement list.
When and if control reaches the end
point of the statement list, control is transferred to the end point of the
block.
The statement list of a block is reachable if the block itself is reachable.
The end point of a block is reachable if the block is empty or if the end
point of the statement list is
reachable.
15.2.1 Statement lists
A statement list consists of one or more statements written in sequence.
Statement lists occur in blocks
(§15.2) and in switch-blocks (§15.7.2).
statement-list:
statement
statement-list statement
A statement list is executed by transferring control to the first
statement. When and if control reaches the end
point of a statement, control is transferred to the next statement. When
and if control reaches the end point of
the last statement, control is transferred to the end point of the
statement list.
A statement in a statement list is reachable if at least one of the
following is true:
? The statement is the first statement and the statement list itself is
reachable.
? The end point of the preceding statement is reachable.
? The statement is a labeled statement and the label is referenced by a
reachable goto statement.
The end point of a statement list is reachable if the end point of the last
statement in the list is reachable.