QA·C Help - 4393

	4393	A composite expression of 'essentially signed' type (%1s) is being cast to a different type category, '%2s'.

Arithmetic type - Composite expressions

This message is issued whenever a composite expression of essentially signed type has been cast to a different essential type category.

It is a common misconception among programmers that the type in which the arithmetic operation is evaluated is influenced by the cast-to type. Instead, the type of the expression is determined solely from the type of its operands after any integral promotion. Therefore, an overflow may occur, which could be avoided if operands were cast instead.

For example:


/*PRQA S 1-9999 ++*/
/*PRQA S 4393 --*/

void foo (unsigned b);

unsigned f4393 (short a)
{
  foo ((unsigned) (a + 1));    /* 4393 */
  
  return ((unsigned) (a * 2)); /* 4393 */
}

For the purposes of QA·C conversion messages, types are ordered according to the configured size (-s option), by default; hence for a typical 32 bit configuration, types int and long will be considered equivalent. However, when the -strictrank option is specified, types will be ordered according to their rank; consequently int will be considered narrower than long.

Personality Groups | Glossary | Message Index

Contents