QA·C Help - 2900

	2900	Constant: Positive integer value truncated by implicit conversion to a smaller unsigned type.

Conversion to unsigned

The value of a non-negative integer constant expression is being implicitly converted to an unsigned type. The value of the expression is larger than the maximum value which can be represented in this type and so truncation will occur using modulo arithmetic.

For example:


/*PRQA S 1255,2017,3120,3211,3306,3408,3606 ++*/


unsigned char  uca = 255;                 /* OK   */
unsigned char  ucb = 256;                 /* 2900 */
unsigned short usa = 65535;               /* OK   */
unsigned short usb = 65536;               /* 2900 */

MISRA-C:2004 Rules applicable to message 2900:

Rule 10.1 (Required)

The value of an expression of integer type shall not be implicitly converted to a different underlying type if: a) it is not a conversion to a wider integer type of the same signedness, or b) the expression is complex, or c) the expression is not constant and is a function argument, or d) the expression is not constant and is a return expression

See also:

2901 Definite: Positive integer value truncated by implicit conversion to a smaller unsigned type.
2902 Apparent: Positive integer value truncated by implicit conversion to a smaller unsigned type.
2903 Suspicious: Positive integer value truncated by implicit conversion to a smaller unsigned type.
2905 Constant: Positive integer value truncated by cast to a smaller unsigned type.
2906 Definite: Positive integer value truncated by cast to a smaller unsigned type.
2907 Apparent: Positive integer value truncated by cast to a smaller unsigned type.
2908 Suspicious: Positive integer value truncated by cast to a smaller unsigned type.

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MISRA-C:2004 Compliance Module 3.2
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