Using ColdFusion MX Functions


A function executes an action and returns the result as output. Functions help reuse the code, leading to modular programming. You create a function once and then call it in multiple instances in a program by using the function name.

Functions may need input data when they're referenced or called. This input data is called a parameter or an argument. Variables, expressions, and other functions can be passed as arguments. A function typically returns a single value, which can be a simple datatype, such as a number or a string, or a complex datatype, such as an array.

CFML provides several built-in functions. These functions are based on the datatypes that they work with, and they're broadly categorized as follows:

  • Mathematical functions

  • String functions

  • Date and time functions

  • Array functions

  • List functions

  • Formatting functions

Note

The Common Function Library at http://www.cflib.org/ includes a number of free libraries for user-defined functions.

Mathematical Functions

Mathematical functions work on numbers. Some of the most common mathematical functions are listed in Table 2.4.

Table 2.4: Common Mathematical Functions

Function

Syntax

Description

Abs

Abs (number)

Returns the absolute value of the number.

BitAnd

BitAnd (number1,number2)

Returns the bitwise AND of two numbers.

Max

Max(number1,number2)

Returns the higher value of the two numbers.

String Functions

String functions are used to manipulate string variables. For example:

 <CFSET Phrase=LCase(Phrase)> 

This function replaces the string value stored in Phrase with all the characters converted to lowercase. Some of the common string type functions are listed in Table 2.5.

Table 2.5: Common String Functions

Function

Syntax

Description

Insert

Insert(substring,string, position)

Inserts a substring in a string after a specified character position

LTrim

LTrim(String)

Returns the string with leading spaces removed

RJustify

RJustify(string,length)

Returns a right-justified string in the specified field length

Date and Time Functions

ColdFusion also has variables that store date and time values, which can range from 100 A.D to 9999 A.D. Date and time functions work with these variables.

For example, the CreateDateTime function is used to create a valid date/time object. The syntax of the CreateDateTime function is

 CreateDateTime(year, month, day, hour, minute, second) 

The year values 0 to 29 are interpreted as 21st-century dates. For example, to create a new date/time variable, use the <CFSET> tag as follows:

 <CFSET DateToday = CreateDateTime(2002,11,25,14,15,50)> 

The preceding code assigns the date 25th November, 2002 and time 14:15:50 to the variable DateToday. You can use the <CFOUTPUT> tag to display the value of a date/time variable. For example, the following code displays the value of the DateToday variable as 2002-11-25 14:15:50:

 <CFOUTPUT>#DateToday#</CFOUTPUT> 

Some of the common date and time functions are listed in Table 2.6.

Table 2.6: Common Date and Time Functions

Function

Syntax

Description

CreateDate

Create(year,month,date)

Returns a valid date object.

DateFormat

DateFormat (date [,mask])

Returns a formatted date/time value. mask is the set of characters that shows how ColdFusion displays a date.

Now

Now()

Returns the current date and time. It's usually used as a parameter to other date and time functions.

Array Functions

ColdFusion offers several functions to work with arrays. Some of the common array functions are described in Table 2.7.

Table 2.7: Common Array Functions

Function

Syntax

Description

ArrayAppend

ArrayAppend (Array,Value)

Adds an element at the end of an array

ArrayPrepend

ArrayAppend (Array,Value)

Adds an element at the beginning of an array

ArrayDeleteAt

ArrayDeleteAt (Array,Position)

Deletes an element at a particular position

ArrayInsertAt

ArrayInsertAt (Array,Position)

Inserts an element at a particular position

List Functions

Some of the common list functions are described in Table 2.8.

Table 2.8: Common List Functions

Function

Syntax

Description

ListLen

ListLen(List,Delimiters)

Returns the number of elements in a list

ListFirst

ListFirst (List,Delimiters)

Returns the first element in a list

ListAppend

ListAppend(List,Element,Delimiters)

Adds an element to a list

Formatting Outputs Using Functions

ColdFusion provides functions to display output in a user-friendly format. Some of the formatting output functions are listed in Table 2.9.

Table 2.9: Common Formatting Functions

Function

Syntax

Description

DollarFormat

DollarFormat(Number)

Returns a number as a string formatted with two decimal places, a thousands separator, and a dollar sign

LSDateFormat

LSDateFormat (date [,mask])

Formats the date portion using the locale convention




Macromedia ColdFusion MX. Professional Projects
ColdFusion MX Professional Projects
ISBN: 1592000126
EAN: 2147483647
Year: 2002
Pages: 200

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