C++ In a Nutshell

Compound Statements

A compound statement is a sequence of zero or more statements enclosed within curly braces. Compound statements are frequently used in selection and loop statements. They enable you to write loop bodies that are more than one statement long, among other things. A compound statement is sometimes called a block.

Here is the syntax of a compound statement:

{statement ... }

or:

{ }

A compound statement can be used as a single statement wherever a statement is called for. A compound statement delimits a declarative scope, that is, any name declared in the compound statement is not visible outside the statement, and names in the statement can hide names from outside the statement. The lifetime of any automatic object declared in a compound statement is confined to that statement. All such objects are destroyed when execution leaves the compound statement for any reason (e.g., branching outside the statement, execution reaches the end of the statement, or an exception is thrown).

Compound statements are most often used as the bodies of selection and loop statements, but you can also stick a compound statement in the middle of a compound statement to restrict the scope of variables that are local to the compound statement. See the examples in this chapter for uses of compound statements.