AUTOSAR C++14 Rule M2-13-2

Octal constants (other than zero) and octal escape sequences (other than "\0" ) shall not be used

Description

Rule Definition

Octal constants (other than zero) and octal escape sequences (other than "\0" ) shall not be used.

Rationale

Octal constants are denoted by a leading zero. A developer or code reviewer can mistake an octal constant as a decimal constant with a redundant leading zero.

Octal escape sequences beginning with \ can also cause confusion. Inadvertently introducing an 8 or 9 in the digit sequence after \ breaks the escape sequence and introduces a new digit. A developer or code reviewer can ignore this issue and continue to treat the escape sequence as one digit.

Polyspace Implementation

The rule checker reports violations on:

Constants beginning with a leading zero.
Escape sequences that begin with a \ followed by a zero.

Troubleshooting

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

Examples

expand all

Use of Octal Constants and Octal Escape Sequences

void func(void) {
  int busData[6];
  
  busData[0] = 100;
  busData[1] = 108;
  busData[2] = 052;      //Noncompliant
  busData[3] = 071;      //Noncompliant
  busData[4] = '\109';   //Noncompliant
  busData[5] = '\100';   //Noncompliant

}

The checker flags all octal constants (other than zero) and all octal escape sequences (other than \0).

In this example:

The octal escape sequence contains the digit 9, which is not an octal digit. This escape sequence has implementation-defined behavior.
The octal escape sequence \100 represents the number 64, but the rule checker forbids this use.

Check Information

Group: Lexical Conventions

Category: Required, Automated

Version History

Introduced in R2019a