constantreference

#constantReference

##Syntax A constantReference is:

constantId { componentSelector }

##Description In a Turing program, a constant is declared and given a name (constantId) and then used. Each use is called a constant reference.

If the constant is an array, record or union, its parts (components) can be selected using subscripts and field names (using componentSelectors). The form of a componentSelector is one of:

(a) (expn {, expn} ) (b) . fieldId

Form (a) is used for subscripting (indexing) arrays. The number of array subscripts must be the same as in the array's declaration. Form (b) is used for selecting a field of a record or union. Component selectors are used in the same manner as variable references. See variableReference for details. See also const declaration and explicitConstant.

##Example

    var radius : real
    const pi := 3.14159     % Constant declaration
    �
    put "Area is: ", pi * radius **2
                        % pi is a constant reference.