QA·C Help - 2895

	2895	Constant: Negative value cast to an unsigned type.

Conversion to unsigned

A constant expression with negative value is being cast to an unsigned type. Is this really intended ? The operation is well defined but is likely at best to be confusing.

The unsigned value which results will the be the value obtained by repeatedly adding or subtracting one more than the maximum value that can be represented in the new type until the value is in the range of the new type.

For example, in the following, if char is an 8 bit type, the value assigned to ucx will be 255.


/*PRQA S 277,2017,3211,3408 ++*/

    unsigned char ucx = (unsigned char)-1;             /* 2895 */

MISRA-C:2004 Rules applicable to message 2895:

Rule 3.1 (Required)

All usage of implementation-defined behaviour shall be documented.

See also:

2890 Constant: Negative value implicitly converted to an unsigned type.
2891 Definite: Negative value implicitly converted to an unsigned type.
2892 Apparent: Negative value implicitly converted to an unsigned type.
2893 Suspicious: Negative value implicitly converted to an unsigned type.
2896 Definite: Negative value cast to an unsigned type.
2897 Apparent: Negative value cast to an unsigned type.
2898 Suspicious: Negative value cast to an unsigned type.

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