MISRA.TOKEN.WRONGESC

Incorrect escape sequence in a literal.

MISRA-C Rule 4.1 (required): Only those escape sequences that are defined in the ISO C standard shall be used.

[Undefined 11; Implementation 11]

Only "simple-escape-sequences" in ISO/IEC 9899:1990 [3—6] Section 6.1.3.4 and '\0' are permitted escape sequences.

All "hexadecimal-escape-sequences" are prohibited.

The "octal-escape-sequences" other than '\0' are also prohibited under Rule 7.1.

MISRA-C++ Rule 2-13-1 (required): Only those escape sequences that are defined in ISO/IEC 14882:2003 shall be used.

[Undefined 2.13.2(3)]

Rationale

The use of an undefined escape sequence leads to undefined behaviour.

The defined escape sequences (ISO/IEC 14882:2003 [1] §2.13.2) are:

\n, \t, \v, \b, \r, \f, \a, \\, \?, \', \", \<Octal Number>, \x<Hexadecimal Number>

Example

void fn ( )
{
   const char_t a[ 2 ] = "\k";    // Non-compliant
   const char_t b[ 2 ] = "\b";    // Compliant
}