Macros are frequently used to make source code more readable. Macro definitions, regardless of whether they expand to a single or multiple statements should not conclude with a semicolon. (See PRE10-C. Wrap multi-statement multistatement macros in a do-while loop.) If required, the semicolon should be included following the macro expansion. Inadvertently inserting a semicolon at the end of the macro definition can unexpectedly change the control flow of the program.
Another way to avoid this problem is to prefer inline or static functions over function-like macros. (See also PRE00-C. Prefer inline or static functions to function-like macros.)
In general, the programmer should ensure that there is no semicolon at the end of a macro definition. The responsibility for having a semicolon where needed during the use of such a macro should be delegated to the person invoking the macro.
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This noncompliant code example creates a macro definition for a for loop in the program. A for loop should require braces, even if it contains only a single body statement. (See EXP19-C. Use braces for the body of an if, for, or while statement.) This macro takes an integer argument, which is the number of times the loop should run. The programmer has provided a semicolon at the end of the macro definition by mistake.
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