What You Must Know About Operators in ColdFusion!

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The fabric of a program consists of expressions, large and small, stitched together with operators and interspersed with functions. The larger expressions as well as the functions themselves may be the result of development from a number of smaller expressions. An understanding of the operators and their correct usage is therefore very essential. This tutorial describes the various operators by presenting comprehensive examples of their usage tested on the MX 6.1 server. <CFScript> will be used in all the examples.

ColdFusion like other programming languages has many operators of the following basic types:

• Arithmetic Operators
• Conditional Operators
• Logical Operators
• String Operator

Arithmetic Operators

When dealing with numbers it is essential to understand how the operators function. Different programming languages use the symbols in slightly different ways. For example the unary operators in ColdFusion do not work the same way as the unary operators in JavaScript. ColdFusion arithmetic operators are mostly binary. Generally, two operands, operand 1 and operand 2 are operated upon by placing the operator in between them, [Operand 1][operator][operand 2] and the resulting value depends on the type of operator.

Operators	Description	Examples & Comments
+, -, *, /	Basic add, subtract, multiply and divide (the right hand operand cannot be zero)	Add: #x# + #y# Subtract: #x# - #y# Multiply: #x# * #y#(x*y = y*x) Divide: #x# / #y#
+, -	Used just to change the sign of variable. i.e, to change 5 to -5	-#x# ( to get a negative of x). <Operator><Operand>
MOD	Remainder left after a division	Example: 5 mod 2 is 1 Sign of modulus is sign of dividend The right operand cannot be zero
^ : the Caret	Exponentiation (raising the power)	Example: #x# ^ 2(exponent is 2) The exponent can be floating point, negative
	Represents integer division	Example: #x# #z# For floating point numbers the integer part is used.

Examples using arithmetic operators

The following example shows several of the operators and their usage.

<!--- Arithmetic Operators --->
<!---Arith.cfm                   --->
<!--- Author: Jay Krishnaswamy --->
<cfscript>
WriteOutput("<b>Arithmetic Operations</b><br/>");
apples=5;
writeoutput("There are " & #apples# & " Apples <br/>");
oranges=10;
writeoutput("There are " & #oranges# & " Oranges<br/>");
bananas=0;
writeoutput("There are " & #bananas# & " bananas<br/><hr width='40%'' 

align=left>");
//Inside <cfscript/> use double slash for comments
//Addition 
WriteOutput("Total of apples and bananas =  " & #apples#+#bananas# );
WriteOutput("<br/>");
WriteOutput("How many more oranges than apples?:  " & # oranges#-#apples#);
WriteOutput("<br/>");
WriteOutput("3 times the number of apples are " & 3*#apples# & " apples");
WriteOutput("<br/>");
WriteOutput("Half the number of oranges are " & #oranges# /2 & " oranges");
WriteOutput("<br/>");
WriteOutput("5 divided by 0 is:" );
WriteOutput( 5/0 & "<br/>");
</cfscript>

<cfset .../> tags and <cfoutput> ..... </cfoutput> tags can also be used, but you may have to write a lot of such tags for the example shown.

Browsing arith.cfm

The following picture shows the display when browsed with FireFox. It appears that FireFox can display the resulting html up to the line which has the error, but IE 6.0 just gives an HTTP 500 error. For displaying in IE 6.0, the last line needs to be modified.

Next: Conditional Operators >>
 

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