7.4 Logical Operators: Operator Precedence
Programming logic is one of the fundamental concepts of computer science and is essential for anyone who wants to learn to program. Among the most important concepts in programming logic are logical operators and operator precedence. In this chapter, we'll explore these concepts in detail.
Logical Operators
Logical operators are used to perform logical operations on Boolean values. The main logical operators are: AND, OR and NOT. The AND operator returns true if both operands are true. The OR operator returns true if at least one of the operands is true. The NOT operator inverts the value of the operand. For example, NOT true returns false and NOT false returns true.
Examples: true AND true = true true AND false = false false AND true = false false AND false = false true OR true = true true OR false = true false OR true = true false OR false = false NOT true = false NOT false = true
Operator Precedence
Operator precedence determines the order in which operations are performed in an expression. For example, in the expression 2 + 3 * 4, multiplication takes precedence over addition, so the expression evaluates as 2 + (3 * 4) = 14, not as (2 + 3) * 4 = 20.
In programming logic, operator precedence is very important to understand how logical expressions are evaluated. The following table shows the precedence of the logical operators, from highest to lowest:
| Operator | Description |
|---|---|
| NOT | Negation |
| AND | Conjunction |
| OR | Disjunction |
This means that in an expression that contains multiple logical operators, the NOT operator is evaluated first, followed by the AND operator, and finally the OR operator. For example, in the expression NOT true AND false OR true, the expression is evaluated as follows:
NOT true AND false OR true = false AND false OR true = false OR true = true
It is important to note that the precedence of operators can be changed using parentheses. For example, in the expression (NOT true) AND (false OR true), the expression is evaluated as follows:
(NOT true) AND (false OR true) = false AND true = false
In summary, understanding logical operators and operator precedence is fundamental to logic programming. They allow you to create complex expressions that can be used to control the flow of a program. Therefore, it is crucial that you understand these concepts before moving on to more advanced topics in logic programming.
