QA·C Help - 3393

	3393	Extra parentheses recommended. An arithmetic operation (* / + -) is the operand of a different operator with the same precedence.

Readability

The order in which operators are processed in this expression is not sufficiently clear and so additional parentheses are recommended. In the absence of parentheses, the sequence is determined by rules of precedence and associativity.

In this expression, there are 2 different arithmetic operators with the same precedence ((* /) or (+ -)) , and the order in which they are evaluated may not be obvious. In fact, the first operator (the left hand one) is evaluated first. Add parentheses to make this clear.

For example:


/*PRQA S 584,2017,3103,3198,3199,3203,3401,3408,3447 ++*/

extern int a;
extern int b;
extern int c;

extern void foo(void)
{
    int r;

    r = a * b / c;                    /* Message 3393 + 3390 */
    r = (a * b) / c;                  /* OK                  */

    r = a / b * c;                    /* Message 3393 + 3390 */
    r = (a / b) * c;                  /* OK                  */

    r = a + b - c;                    /* Message 3393 + 3390 */
    r = (a + b) - c;                  /* OK                  */

    r = a - b + c;                    /* Message 3393 + 3390 */
    r = (a - b) + c;                  /* OK                  */

}

See also:

3389 Extra parentheses recommended to clarify the ordering of a % operator and another arithmetic operator (* / % + -).
3391 Extra parentheses recommended. A conditional operation is the operand of another conditional operator.
3392 Extra parentheses recommended. A shift, relational or equality operation is the operand of a second identical operator.
3394 Extra parentheses recommended. A shift, relational or equality operation is the operand of a different operator with the same precedence.
3395 Extra parentheses recommended. A * or / operation is the operand of a + or - operator.
3396 Extra parentheses recommended. A binary operation is the operand of a conditional operator.
3397 Extra parentheses recommended. A binary operation is the operand of a binary operator with different precedence.

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