MISRA C++:2023 Rule 5.13.3

Octal constants shall not be used

Since R2024b

Description

Rule Definition

Octal constants shall not be used.

Rationale

Octal constants are denoted by a leading zero. You can confuse an octal constant as a decimal constant with a redundant leading zero.

Octal escape sequences beginning with \ are compliant.

Polyspace Implementation

The rule checker reports violations on constants beginning with a leading 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

Use of Octal Constants and Octal Escape Sequences

The checker flags all octal constants (other than zero).

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 is compliant with this rule.

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

}

Check Information

Group: Lexical Conventions

Category: Required

Version History

Introduced in R2024b