CERT C: Rec. DCL18-C

Do not begin integer constants with 0 when specifying a decimal value

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Description

Rule Definition

Do not begin integer constants with 0 when specifying a decimal value.¹

Polyspace Implementation

The rule checker checks for Use of octal constants.

Examples

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Use of octal constants

Issue

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

Risk

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

Example - Use of octal constants

#define CST     021              /* Noncompliant */
#define VALUE   010              /* Noncompliant */
#if 010 == 01                    /* Noncompliant*/
#define CST 021                  /* Noncompliant */
#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: Rec. 02. Declarations and Initialization (DCL)

Version History

Introduced in R2019a

¹ This software has been created by MathWorks incorporating portions of: the “SEI CERT-C Website,” © 2017 Carnegie Mellon University, the SEI CERT-C++ Web site © 2017 Carnegie Mellon University, ”SEI CERT C Coding Standard – Rules for Developing safe, Reliable and Secure systems – 2016 Edition,” © 2016 Carnegie Mellon University, and “SEI CERT C++ Coding Standard – Rules for Developing safe, Reliable and Secure systems in C++ – 2016 Edition” © 2016 Carnegie Mellon University, with special permission from its Software Engineering Institute.

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