MISRA C:2012 Rule 7.1

Octal constants shall not be used

Description

Rule Definition

Octal constants shall not be used¹ .

Rationale

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

Polyspace Implementation

If you use octal constants in a macro definition, the rule checker flags the issue even if the macro is not used.

Troubleshooting

If you expect a rule violation but do not see it, refer to Diagnose Why Coding Standard Violations Do Not Appear as Expected.

Examples

Example - Use of octal constants

#define CST     021              /* Noncompliant */
#if 010 == 01                    /* Noncompliant*/
#define CST 021                  
#endif

extern short code[5];
static char* str2 = "abcd\0efg";  /* Compliant */

void main(void) {
    int value1 = 0;               /* Compliant */
    int value2 = 01;              /* Noncompliant*/
    int value3 = 1;               /* Compliant */
    int value4 = '\109';          /* Compliant */

    code[1] = 109;                /* Compliant     - decimal 109 */
    code[2] = 100;                /* Compliant     - decimal 100 */
    code[3] = 052;                /* Noncompliant */
    code[4] = 071;                /* Noncompliant */

    if (value1 != CST) {          
        value1 = !(value1 != 0);  /* Compliant */
    }
}

In this example, Polyspace^® flags the use of octal constants.

Check Information

Group: Literals and Constants

Category: Required

AGC Category: Advisory

Version History

Introduced in R2014b

R2025a: Violation not reported on unused macros defining octal constants

Polyspace does not report a violation if a macro defines an octal constant but it is not used in the code. The violation is reported on the macro definition.

#define MY_OCTAL 0100       //Noncompliant
#define OCTAL_NOT_USED 0100
void func(void) {

	int a = MY_OCTAL;

}

In this code, the definition of the macro MY_OCTAL is reported as a violation but the definition of the unused macro OCTAL_NOT_USED is not flagged.