ENSC 104: DIGITAL COMPUTER PROGRAMMING

PRECEDENCE

Lecture Topics

Rules of Operator Precedence
- Operators in expressions contained within parenthesis are evaluated first. Parenthesis may be used to force the order of evaluation to occur in any sequence desired. Parenthesis have the highest level of precedence.
- Multiplication, division, and modulus are at the next level of precedence. These are operators are evaluated from left to right. These operators are all on the same level of precedence.
- Addition and subtraction have the lowest precedence of these operators. They are evaluated last and in a left to right fashion.
- Example #1
```
          u = 5 * 6 + 20 / 4 - 8 % 3;

            = 30 + 20 / 4 - 8 % 3;

            = 30 + 5 - 8 % 3;

            = 30 + 5 - 2;

            = 35 - 2;

            = 33;

          
```
- Example #2
```
          u = 5 * ((6 + 20) / (4 - 8)) % 3;

          u = 5 * (26 / (4 - 8)) % 3;

          u = 5 * (26 / -4) % 3;

          u = 5 * -6 % 3;

          u = -30 % 3;

          u = 0;
          
```

Operators	Associativity	Type
()	left-to-right	parenthesis
*, /, %	left-to-right	multiplicative
+, -	left-to-right	additive
-	right-to-left	unary

Demonstration Programs

Program 1.7a: Precedence