(1) See
Expression Studio.
(2) In programming, a line of source code that returns a value when executed. An expression can comprise any combination of variables, values, operators and functions. For example,
a=b+c and
price=2*cost are expressions. The more complicated expression
(strlen(text_string)*2) is a C example that uses a string length function and returns a value that is twice the number of characters in the string of text. See
regular expression.