Trusted answers to developer questions
Trusted Answers to Developer Questions

Related Tags

euphoria
communitycreator

How to create a user-defined data type in Euphoria

NDUKWE CHIDERA K.

Overview

A data type is used in Euphoria to specify the allowable type of data for a particular variable. Euphoria Language is a static typed language. This means that every variable must be declared, stating the data type first before assigning any value and using such a variable.

Users can be more specific about the data type in their programs by defining their own data types on-top of the existing Euphoria primitive types.

This is achieved using the type() function following the syntax that is explained below.

The type() function is utilized to create a custom user type. This function takes the identifier for the variable to be typed, with the function body containing any rule for the data type variables as arguments.

Syntax

type type_identifier(declare_base_type)
--optional range of legal values
end type
  • type: Keyword used to call the type function.
  • type_identifier: The name we wish to give the new type to be created
  • optional range or legal values: The rule that governs the legal value if specified.
  • declare_base_type: Any of the basic types available in Euphoria. Every custom type usually has base types on top of which they are created.
  • end type: The statement that comes to the end of the type creation.

Example

In the demonstration below, there is a sample creation of a custom type age. And how it is used in a procedure, which is also possible in a function and other expressions:

type age(integer y) --declaring a custom data type
         return y >= 18 and y <= 50 --setting the legal values
     end type
age h1, h2 --this is how you can declare variables of type age 
h1 = 40
--h2 = 100
print(1,  h1)
puts(1, '\n')   
--using these user defined types in functions and others
procedure what_age(age your_age)
  printf(1,"You are %d years young",your_age)
end procedure
what_age(50)

Explanation

In the code above:

  • Line 1 We declare a type: age with the base type of int.
  • Line 2 We return the allowable value for the type created.
  • Line 4: We declare two variables h1 and h2 as age type.
  • Lines 5 and 6: We assign values to the variables. Although line 6 is commented out because it causes a type check error to be thrown because the value is not allowed.
  • Line 10: We create a procedure what_ageand pass your_age as a parameter, which is of type age.
  • Line 12: We end the procedure with end procedure.
  • Line 13: We make a call to the procedure.

RELATED TAGS

euphoria
communitycreator
RELATED COURSES

View all Courses

Keep Exploring