What is a compound statement?

A compound statement consists of none or more C++ statements enclosed within a set of braces: {}. It is an essential concept in C++ and is central to the idea of nesting constructs. For example, the if statement has the form:-

if ( expression ) statement

which would severely limit its use were it not for the fact that a compound statement is itself a statement. Consequently any number of statements can be enclosed within a set of braces, including other if and compound ones, and the resulting compound statement used with the if statement. For example:-