CERT C: Rec. PRE07-C

Avoid using repeated question marks

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Description

Rule Definition

Avoid using repeated question marks.¹

Polyspace Implementation

The rule checker checks for Use of trigraphs.

Examples

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Use of trigraphs

Issue

The issue occurs when you use trigraphs in your code.

The Polyspace^® analysis converts trigraphs to the equivalent character for the defect analysis. However, Polyspace also raises a MISRA™ violation.

The standard requires that trigraphs must be transformed before comments are removed during preprocessing. Therefore, Polyspace raises a violation of this rule even if a trigraph appears in code comments.

Risk

You denote trigraphs with two question marks followed by a specific third character (for instance,'??-' represents a '~' (tilde) character and '??)' represents a ']'). These trigraphs can cause accidental confusion with other uses of two question marks.

Note

Digraphs (<: :>, <% %>, %:, %:%:) are permitted because they are tokens.

Check Information

Group: Rec. 01. Preprocessor (PRE)

Version History

Introduced in R2019a

¹ This software has been created by MathWorks incorporating portions of: the “SEI CERT-C Website,” © 2017 Carnegie Mellon University, the SEI CERT-C++ Web site © 2017 Carnegie Mellon University, ”SEI CERT C Coding Standard – Rules for Developing safe, Reliable and Secure systems – 2016 Edition,” © 2016 Carnegie Mellon University, and “SEI CERT C++ Coding Standard – Rules for Developing safe, Reliable and Secure systems in C++ – 2016 Edition” © 2016 Carnegie Mellon University, with special permission from its Software Engineering Institute.

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