QA·C Help - 1881

	1881	The operands of this equality operator are expressions of different 'essential type' categories (%1s and %2s).

Arithmetic type - Balancing

This message is issued when an equality operator is used with operands of different essential type categories.

For example:


/*PRQA S 1-9999 ++*/
/*PRQA S 1881, 1803, 1823 --*/

_Bool             boa;
char              pca;
enum E {ONE, TWO} ena;
enum F {UNO, DUE} enb;
int               sia;
unsigned          uia;
float             fta;

void f1881 (void)
{
  if (boa == pca) ;  /* 1881 */
  if (boa == ena) ;  /* 1881 */
  if (boa == sia) ;  /* 1881 */
  if (boa == uia) ;  /* 1881 */
  if (boa == fta) ;  /* 1881 */

  if (pca == ena) ;  /* 1881 */
  if (pca == sia) ;  /* 1881 */
  if (pca == uia) ;  /* 1881 */
  if (pca == fta) ;  /* 1881 */

  if (ena == enb) ;  /* 1881 */
  if (ena == sia) ;  /* 1881 */
  if (ena == uia) ;  /* 1881 */
  if (ena == fta) ;  /* 1803 */

  if (sia == uia) ;  /* 1823 */
  if (sia == fta) ;  /* 1803 */

  if (uia == fta) ;  /* 1803 */
}

MISRA-C:2004 Rules applicable to message 1881:

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
Rule 10.2 (Required)	The value of an expression of floating type shall not be implicitly converted to a different type if: a) it is not a conversion to a wider floating type, or b) the expression is complex, or c) the expression is a function argument, or d) the expression is a return expression

See also:

1803 The %1s operand (essential type: '%2s') will be implicitly converted to a floating type, '%3s', in this equality operation.
1823 The %1s operand is non-constant and 'essentially signed' (%2s) but will be implicitly converted to an unsigned type (%3s) in this equality operation.

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MISRA-C:2004 Compliance Module 3.2
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