Expressions; Operator Types - MACROMEDIA COLDFUSION MX 61-DEVELOPING COLDFUSION MX Develop Manual

Expressions

ColdFusion expressions consist of operands and operators. Operands are comprised of constants
and variables. Operators, such as the multiplication symbol, are the verbs that act on the
operands; functions are a form of operator.
The simplest expression consists of a single operand with no operators. Complex expressions have
multiple operators and operands. The following are all ColdFusion expressions:
12
MyVariable
(1 + 1)/2
"father" & "Mother"
Form.divisor/Form.dividend
Round(3.14159)
Operators act on the operands. Some operators, such as functions with a single argument, take a
single operand. Many operators, including most arithmetic and logical operators, take two
operands. The following is the general form of a two-operand expression:
Expression Operator Expression
Note that the operator is surrounded by expressions. Each expression can be a simple operand
(variable or constant) or a subexpression consisting of more operators and expressions. Complex
expressions are built up using subexpressions. For example, in the expression (1 + 1)/2, 1 + 1 is a
subexpression consisting of an operator and two operands.

Operator types

ColdFusion has four types of operators:
•
Arithmetic
•
Boolean
•
Decision (or comparison)
•
String
Functions also can be viewed as operators because they act on operands.
Arithmetic operators
The following table describes the arithmetic operators:
Operator Description
+ - * / Basic arithmetic: Addition, subtraction, multiplication, and division. In division, the right
operand cannot be zero.
+ - Unary arithmetic: Set the sign of a number.
MOD Modulus: Return the remainder after a number is divided by a divisor. The result has the
same sign as the divisor. The right should be an integer; using a non-numeric value
causes an error, and if you specify a real number, ColdFusion ignores the fractional part
(for example, 11 MOD 4 is 3).
84 Chapter 4: Using Expressions and Pound Signs