Page History

C99 The C Standard defines octal constants as a 0 followed by octal digits (0 1 2 3 4 5 6 7). This can lead to programming errors 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;

Wiki MarkupAlthough it may appear that 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, don't 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;

...

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

Bibliography

\[[ISO/IEC 9899:1999|cplusplus:AA. C References#ISO/IEC 9899-1999]\] Section 6.4.4.1  "Integer constants"
\[MISRA 04\] Section 6.7 Rule 7.1

Automated Detection

Related Guidelines

...

Image Added Image Added Image AddedImage Removed      02. Declarations and Initialization (DCL)      DCL19-C. Use as minimal a scope as possible for all variables and functions