HP C A.06.05 Reference Manual

Statements
Expression and Null Statements
Chapter 6 151
Expression and Null Statements
Syntax
expression-statement ::=
[ expression ];
Description
C expressions can be statements. A null statement is simply a semicolon by itself.
You can use any valid expression as an expression statement by terminating it with a
semicolon. Expression statements are evaluated for their side effects; such as assignment or
function calls. If the expression is not specified, but the semicolon is still provided, the
statement is treated as a null statement.
Null statements are useful for specifying no-operation statements. No-operation statements
are often used in looping constructs where all of the work of the statement is done without an
additional statement.
Example
A program fragment that sums up the contents of an array named x containing 10 integers
might look like this:
for(i=0,s=0; i<10; s+=x[i++]);
The syntax of the for statement requires a statement following the closing ) of the for. A null
statement (;) satisfies this syntax requirement.