84
Chapter 4: Using Expressions and Pound Signs
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).
Содержание ColdFusion MX
Страница 1: ...Developing ColdFusion MX Applications...
Страница 22: ...22 Contents...
Страница 38: ......
Страница 52: ...52 Chapter 2 Elements of CFML...
Страница 162: ......
Страница 218: ...218 Chapter 10 Writing and Calling User Defined Functions...
Страница 250: ...250 Chapter 11 Building and Using ColdFusion Components...
Страница 264: ...264 Chapter 12 Building Custom CFXAPI Tags...
Страница 266: ......
Страница 314: ...314 Chapter 14 Handling Errors...
Страница 344: ...344 Chapter 15 Using Persistent Data and Locking...
Страница 349: ...About user security 349...
Страница 357: ...Security scenarios 357...
Страница 370: ...370 Chapter 16 Securing Applications...
Страница 388: ...388 Chapter 17 Developing Globalized Applications...
Страница 408: ...408 Chapter 18 Debugging and Troubleshooting Applications...
Страница 410: ......
Страница 426: ...426 Chapter 19 Introduction to Databases and SQL...
Страница 476: ...476 Chapter 22 Using Query of Queries...
Страница 534: ...534 Chapter 24 Building a Search Interface...
Страница 556: ...556 Chapter 25 Using Verity Search Expressions...
Страница 558: ......
Страница 582: ...582 Chapter 26 Retrieving and Formatting Data...
Страница 668: ......
Страница 734: ...734 Chapter 32 Using Web Services...
Страница 760: ...760 Chapter 33 Integrating J2EE and Java Elements in CFML Applications...
Страница 786: ...786 Chapter 34 Integrating COM and CORBA Objects in CFML Applications...
Страница 788: ......
Страница 806: ...806 Chapter 35 Sending and Receiving E Mail...