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MISRA C++:2008 Rule 3-9-3

The underlying bit representations of floating-point values shall not be used

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Description

Rule Definition

The underlying bit representations of floating-point values shall not be used.

Rationale

The underlying bit representations of floating point values vary across compilers. If you directly use the underlying representation of floating point values, your program is not portable across implementations.

Polyspace Implementation

The rule checker flags conversions from pointers to floating point types into pointers to integer types, and vice versa.

Troubleshooting

If you expect a rule violation but Polyspace® does not report it, see Diagnose Why Coding Standard Violations Do Not Appear as Expected.

Examples

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float fabs2(float f) {
    unsigned int* ptr = reinterpret_cast <unsigned int*> (&f); //Noncompliant
    *(ptr + 3) &= 0x7f;
    return f;
}

In this example, the reinterpret_cast attempts to cast a floating-point value to an integer and access the underlying bit representation of the floating point value.

Check Information

Group: Basic Concepts
Category: Required

Version History

Introduced in R2013b

See Also

Topics