User Guide

Table Of Contents

Using number signs 81

Using number signs

Number signs (#) have a special meaning in CFML. When the ColdFusion server encounters

number signs in CFML text, such as the text in a

cfoutput tag body, it checks to see if the text

between the number signs is either a variable or a function.

Tip: Number signs are also called pound signs.

Is so, it replaces the text and surrounding number signs with the variable value or the result of the

function. Otherwise, ColdFusion generates an error.

For example, to output the current value of a variable named

Form.MyFormVariable, you delimit

(surround) the variable name with number signs:

<cfoutput>Value is #Form.MyFormVariable#</cfoutput>

In this example, the variable Form.MyFormVariable is replaced with the value assigned to it.

Follow these guidelines when using number signs:

• Use number signs to distinguish variables or functions from plain text.

• Surround only a single variable or function in number signs; for example, #Variables.myVar#

or #Left(myString, position)#. (However, a function in number signs can contain nested

functions, such as #Left(trim(myString), position)#.

• Do not put complex expressions, such as 1 + 2 in number signs. Although this is allowed in

a cfoutput block, such as <cfoutput>One plus one is #1 + 1#</cfoutput>, doing so mixes logic

and presentation.

• Use number signs only where necessary, because unneeded number signs slow processing.

The following sections provide more details on how to use number signs in CFML. For a

description of using number signs to create variable names, see “Using number signs to construct

a variable name in assignments” on page 85.

Using number signs in ColdFusion tag attribute values

You can put variables, functions, or expressions inside tag attributes by enclosing the variable or

expression with number signs. For example, if the variable CookieValue has the value

"MyCookie", the following line sets the

cfcookie value attribute to "The value is MyCookie":

You can optionally omit quotation marks around variables used as attribute values as shown in the

following example:

However, surrounding all attribute values in quotation marks is more consistent with HTML

coding style.

If you use string expressions to construct an attribute value, as shown in the following example,

the strings inside the expression use single quotation marks (') to differentiate the quotation

marks from the quotation marks that surround the attribute value.