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The C Standard defines octal constants as a 0 followed by octal digits (0 1 2 3 4 5 6 7). Programming errors can occur when decimal values are mistakenly specified as octal constants.

Noncompliant Code Example

In this noncompliant code example, a decimal constant is mistakenly prefaced with zeros so that all the constants are a fixed length:

i_array[0] = 2719;
i_array[1] = 4435;
i_array[2] = 0042;

Although it may appear that i_array[2] is assigned the decimal value 42, it is actually assigned the decimal value 34.

Compliant Solution

To avoid using wrong values and to make the code more readable, do not preface constants with zeroes if the value is meant to be decimal:

i_array[0] = 2719;
i_array[1] = 4435;
i_array[2] =   42;

Risk Assessment

Misrepresenting decimal values as octal can lead to incorrect comparisons and assignments.

Automated Detection

Related Guidelines