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Noncompliant Code Example
In this noncompliant code example, variables are defined with names reserved for the implementation.
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Noncompliant Code Example (Header Guard)
A common but non-compliant noncompliant practice is to choose a reserved name for a macro used in a preprocessor conditional guarding against multiple inclusion of a header file. See also PRE06-C. Enclose header files in an inclusion guard. The name may clash with reserved names defined by the implementation of the C standard library in its headers, or with reserved names implicitly predefined by the compiler even when no C standard library header is included.
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Compliant Solution (Header Guard)
The This compliant solution avoids using leading or trailing underscores in the name of the header guard.
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Noncompliant Code Example (Global Variable)
In this noncompliant code example, a variable beginning with an underscore is defined with implicit global scope.
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This code might have been safe if the C file containing it includes no header files. However, it requires that the header stddef.h be included in order to define size_t. Including any standard header files will introduce a potential name clash. Consequently it is not safe to prepend any identifier with an underline, even if its usage is confined to a single file.
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