ColdFusion expressions consist of operands and operators. Constants and variables are operands. Operators, such as the multiplication sign, 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 a++ (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 twooperand expression:
Expression Operator Expression
Expressions surround the operator. 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.
ColdFusion has Five types of operators:
 Arithmetic
 Boolean
 Decision (or comparison)
 String
 Ternary
Functions also can be viewed as operators because they act on operands.
Operator 
Description 

+  * / 
Basic arithmetic: Addition, subtraction, multiplication, and division. In division, the right operand cannot be zero. 
++ – 
Increment and decrement. Increase or decrease the variable by one.These operators can be used for preincrementing or decrementing (as in {{ x = ++ i}}), where the variable is changed before it is used in the expression. They can also be used for postincrementing or decrementing (as in x = i+), where the value is changed after it is used in the expression. If the value of the variable i is initially 7, for example, the value of x in x = ++i is 8 after expression evaluation, but in x=i, the value of x is 7. In both cases, the value of i becomes 8.These operators cannot be used with expressions that involve functions, as in f().a. Also, you can use an expression such as x, but x and +x cause errors, because their meanings are ambiguous. You can use parentheses to group the operators, as in (x) or (++x), however. 
+= = *= /= %= 
Compound assignment operators. The variable on the right is used as both an element in the expression and the result variable. Thus, the expression a += b is equivalent to a = a +b. 
+  
Unary arithmetic: Set the sign of a number. 
MOD or % 
Modulus: Return the remainder after a number is divided by a divisor. The result has the same sign as the divisor. The value to the right of the operator should be an integer; using a nonnumeric value causes an error, and if you specify a real number, ColdFusion ignores the fractional part (for example, 11 MOD 4.7 is 3). 

Integer division: Divide an integer by another integer. The result is also an integer; for example, 9\4 is 2. The right operand cannot be zero. 
^ 
Exponentiation: Return the result of a number raised to a power (exponent). Use the caret character (^) to separate the number from the power; for example, 2^3 is 8. Real and negative numbers are allowed for both the base and the exponent. However, any expression that equates to an imaginary number, such 1^.5 results in the string "1.#IND. ColdFusion does not support imaginary or complex numbers. 
Boolean, or logical, operators perform logical connective and negation operations. The operands of Boolean operators are Boolean (True/False) values. The following table describes the Boolean operators:
Operator 
Description 

NOT 
Reverse the value of an argument. For example, NOT True is False and the inverse. 
AND 
Return True if both arguments are True; return False otherwise. For example, True AND True is True, but True AND False is False. 
OR 
Return True if any of the arguments is True; return False otherwise. For example, True OR False is True, but False OR False is False. 
XOR 
Exclusive or: Return True if one of the values is True and the other is False. Return False if both arguments are True or both are False. For example, True XOR True is False, but True XOR False is True. 
EQV 
Equivalence: Return True if both operands are True or both are False. The EQV operator is the opposite of the XOR operator. For example, True EQV True is True, but True EQV False is False. 
IMP 
Implication: The statement A IMP B is the equivalent of the logical statement "If A Then B." A IMP B is False only if A is True and B is False. It is True in all other cases. 
The ColdFusion decision, or comparison, operators produce a Boolean True/False result. Many types of operation have multiple equivalent operator forms. For example, IS and EQ perform the same operation. The following table describes the decision operators:
Operator 
Description 

IS EQUAL 
Perform a caseinsensitive comparison of two values. Return True if the values are identical. 
IS NOT 
Opposite of IS. Perform a caseinsensitive comparison of two values. Return True if the values are not identical. 
CONTAINS 
Return True if the value on the left contains the value on the right. 
DOES NOT CONTAIN 
Opposite of CONTAINS. Return True if the value on the left does not contain the value on the right. 
GREATER THAN 
Return True if the value on the left is greater than the value on the right. 
LESS THAN 
Opposite of GREATER THAN. Return True if the value on the left is smaller than the value on the right. 
GREATER THAN OR EQUAL TO 
Return True if the value on the left is greater than or equal to the value on the right. 
LESS THAN OR EQUAL TO 
Return True if the value on the left is less than or equal to the value on the right. 
Note:
In CFScript expressions only, you can also use the following decision operators. You cannot use them in expressions in tags. == (EQ), != (NEQ), > (GT), < (LT), >= (GTE), and <= (LTE).
The following rules apply to decision operators:
 When ColdFusion evaluates an expression that contains a decision operator other than CONTAINS or DOES NOT CONTAIN, it first determines if the data can be converted to numeric values. If they can be converted, it performs a numeric comparison on the data. If they cannot be converted, it performs a string comparison. This can sometimes result in unexpected results. For more information on this behavior, see Evaluation and type conversion issues in Data type conversion.
When ColdFusion evaluates an expression with CONTAINS or DOES NOT CONTAIN it does a string comparison. The expression A CONTAINS B evaluates to True if B is a substring of A. Therefore an expression such as the following evaluates as True:
123.45 CONTAINS 3.4 
When a ColdFusion decision operator compares strings, it ignores the case. As a result, the following expression is True:
"a" IS "A"
When a ColdFusion decision operator compares strings, it evaluates the strings from left to right, comparing the characters in each position according to their sorting order. The first position where the characters differ determines the relative values of the strings. As a result, the following expressions are True:
"abde" LT "ac"
Operator 
Description 

& 
Concatenates strings. 
&= 
Compound concatenation. The variable on the right is used as both an element in the concatenation operation and the result variable. Thus, the expression a &= b is equivalent to a = a & b.An expression can have only one compound assignment operator. 
Note:
In a Query of Queries, you use  as the concatenation operator.
The ternary operator is a decision operator with three operands. It assigns a variable a value based on a Boolean expression. The operator has the form
(Boolean expression)? expression1 : expresson2
If the Boolean expression evaluates to true, the operator result is expression1; otherwise, it is expression2
For example
<cfset c = (a GT b)? a : b >
If a is greater than b, c is assigned the value of a; otherwise, c is assigned the value of b.
The parentheses can contain any expression that evaluates to a Boolean value, and a and b can be any valid expression. You can nest this operator inside other expressions.
The order of precedence controls the order in which operators in an expression are evaluated. The order of precedence is as follows. (Some alternative names for operators, such as EQUALS and GREATER THAN OR EQUAL TO are omitted for brevity.)
^ *, / \ MOD +,  & EQ, NEQ, LT, LTE, GT, GTE, CONTAINS, DOES NOT CONTAIN, ==, !=, >, >=, <, <= NOT, ! AND, && OR,  XOR EQV IMP
To enforce a nonstandard order of evaluation, parenthesize expressions. For example:
 6  3 * 2 is equal to 0
 (6  3) * 2 is equal to 6
You can nest parenthesized expressions. When in doubt about the order in which operators in an expression are evaluated, use parentheses to force the order of evaluation.
Functions are a form of operator. Because ColdFusion functions return values, you can use function results as operands. Function arguments are expressions. For example, the following are valid expressions:
 Rand()
 UCase("This is a text: ") & ToString(123 + 456)
Usage 
Example 

No arguments 
Function() 
Basic format 
Function(Data) 
Nested functions 
Function1(Function2(Data)) 
Multiple arguments 
Function(Data1, Data2, Data3) 
String arguments 
Function('This is a demo')Function(This is a demo) 
Arguments that are expressions 
Function1(X*Y, Function2("Text")) 
<cfset myDate = DateFormat(Now(), "mmmm d, yyyy")>
You can use the values returned by functions directly to create more complex expressions, as in the following example:
Abs(Myvar)/Round(3.14159)
For more information on how to insert functions in expressions, see Using number signs.
Some functions take optional arguments after their required arguments. If omitted, all optional arguments default to a predefined value. For example:
 Replace("Eat and Eat", "Eat", "Drink") returns "Drink and Eat"
 Replace("Eat and Eat", "Eat", "Drink", "All") returns "Drink and Drink"
The difference in the results is because the Replace function takes an optional fourth argument that specifies the scope of replacement. The default value is "One," which explains why only the first occurrence of "Eat" was replaced with "Drink" in the first example. In the second example, a fourth argument causes the function to replace all occurrences of "Eat" with "Drink".
It is important to remember that ColdFusion evaluates function attributes as expressions before it executes the function. As a result, you can use any ColdFusion expression as a function attribute. For example, consider the following lines:
<cfset myStringVar = UCase(firstVariable & " more sleep!")>
When ColdFusion server executes the second line, it does the following:
 Identifies an expression with a string concatenation.
 Evaluates the firstVariable variable as the string "we all need".
 Concatenates "we all need" with the string "more sleep!" to get "we all need more sleep!".
 Passes the string "we all need more sleep!" to the UCase function.
 Executes the UCase function on the string argument "we all need more sleep!" to get "WE ALL NEED MORE SLEEP!".
 Assigns the string value "WE ALL NEED MORE SLEEP!" to the variable myStringVar.
ColdFusion completes steps 13 before running the function.
You can chain assignments to assign the same value to multiple variables in a single statement. This includes chain assignments for the results of an expression. The following code displays a chain assignment:
a=b=c=d*5
You can use the var operator in multiple assignments, but the variables with this operator must precede all others. For example:
//The following line is valid. var a = var b = c = d*5 //The following line is not valid. // a = b = var c = d*5