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The C ISO 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 in constants that are meant to be taken by their decimal value, especially when declaring multiple constants and preserving fixed length.

Noncompliant code example

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 lengthWhen using integer constants, for example, as in:

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

It seems as if the element in Although it may appear that i_array is meant to hold [2] is assigned the decimal value 42 instead of what actually gets stored, which is the value 32, it is actually assigned the decimal value 34.

Compliant

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Solution

To avoid using wrong values and to make the code more readable, don't pad 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

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Assessment

Misinterpreting Misrepresenting decimal values as octal could can lead to an incorrect value being written into codeincorrect comparisons and assignments.

References

Automated Detection

Related Guidelines

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