AUTOSAR C++14 Rule A21-8-1

Arguments to character-handling functions shall be representable as an unsigned char

Description

Rule Definition

Arguments to character-handling functions shall be representable as an unsigned char.

Rationale

You cannot use plain char variables as arguments to character-handling functions declared in <cctype>, for instance, isalpha() or isdigit(). On certain platforms, plain char variables can have negative values that cannot be represented as unsigned char or EOF, resulting in undefined behavior.

Polyspace Implementation

The check raises a flag when you use a signed or plain char variable with a negative value as argument to a character-handling function.

Troubleshooting

If you expect a rule violation but Polyspace^® does not report it, see Diagnose Why Coding Standard Violations Do Not Appear as Expected.

Check Information

Group: Strings library

Category: Required, Automated

Version History

Introduced in R2019a