An expression in C can also be a statement. A null
statement is an expression statement with no expression
and it is used to provide a null operation.
Description |
 |
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. For 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++]); |
No additional statement is necessary to specify the required
function, however, the syntax of the for
statement requires a statement following the closing )
of the for. To
meet this syntax requirement, you can use a null statement.
