In addition to the comparison operators, which can be used on string values, the concatenation operator (&) concatenates two string values together, returning another string that is the union of the two operand strings. For example, “my ” & “string” returns the string “my string”.

The shorthand assignment operator &= can also be used to concatenate strings. For example, if the variable mystring has the value “alpha”, then the expression mystring &= “bet” evaluates to “alphabet” and assigns this value to mystring. This expression can be used in all CFML expressions.

<cfscript>
mystring = "Alpha";
mystring &= "bet";
</cfscript>
 
<cfdump var="#variables#" label="Concatenating Strings" />

This returns the following output:

In my first post in this series, I introduced Using JavaScript Arithmetic Operators in ColdFusion 8. Now we’ll concentrate on Assignment operators.

An assignment operator assigns a value to its left operand based on the value of its right operand.

The basic assignment operator is equal (=), which assigns the value of its right operand to its left operand. That is, x = y assigns the value of y to x. The other assignment operators are usually shorthand for standard operations, as shown in the following table.

In unusual situations, the assignment operator is not identical to the Meaning expression in the above table. When the left operand of an assignment operator itself contains an assignment operator, the left operand is evaluated only once. For example:

<cfscript>
a[i++] += 5 //i is evaluated only once
a[i++] = a[i++] + 5 //i is evaluated twice
</cfscript>