Conventional programming languages enforce strict rules about mixing objects of different types in expressions. For example, in a language such as C++ or Basic, the expression ("8" * 10) produces an error because the multiplication operator requires two numerical operands and "8" is a string. When you program in such languages, you must convert between data types to ensure error-free program execution. For example, the previous expression might have to be written as (ToNumber("8") * 10).

In ColdFusion, however, the expression ("8" * 10) evaluates to the number 80 without generating an error. When ColdFusion processes the multiplication operator, it automatically attempts to convert its operands to numbers. Since "8" can be successfully converted to the number 8, the expression evaluates to 80.

ColdFusion processes expressions and functions in the following sequence:

1. For each operator in an expression, it determines the required operands. (For example, the multiplication operator requires numeric operands and the CONTAINS operator requires string operands.)

   For functions, it determines the type required for each function argument. (For example, the Min function requires two numbers as arguments and the Len function requires a string.)

2. It evaluates all operands or function arguments.
3. It converts all operands or arguments whose types differ from the required type. If a conversion fails, it reports an error.