Definition of dray. : a vehicle used to haul goods; especially : a strong cart or wagon without sides.
Expressions versus Equations. A difference between expressions and equations is what each represents. An expression shows a math relationship. One key to an expression is that there is no solution. An expression does not have an answer. An expression, however, can be evaluated. To evaluate an expression, substitute values for the variables.
Next: Operators Up: Scientific programming in C Previous: Variables. An expression represents a single data item--usually a number. The expression may consist of a single entity, such as a constant or variable, or it may consist of some combination of such entities, interconnected by one or more operators. Expressions can also represent logical conditions which are either true or false.