Records

From Lazarus wiki
Revision as of 22:09, 25 November 2007 by Kees (talk | contribs)

5E - Records (author: Tao Yue, state: unchanged)

A record allows you to keep related data items in one structure. If you want information about a person, you may want to know name, age, city, state, and zip.

To declare a record, you'd use:

TYPE
  TypeName = record
     identifierlist1 : datatype1;
     ...
     identifierlistn : datatypen;
  end;

For example:

type
  InfoType = record
      Name : string;
      Age : integer;
      City, State : String;
      Zip : integer;
  end;

Each of the identifiers Name, Age, City, State, and Zip are referred to as fields. You access a field within a variable by:

VariableIdentifier.FieldIdentifier

A period separates the variable and the field name.

There's a very useful statement for dealing with records. If you are going to be using one record variable for a long time and don't feel like typing the variable name over and over, you can strip off the variable name and use only field identifiers. You do this by:

WITH RecordVariable DO
BEGIN
  ...
END;

Example:

with Info do
begin
  Age := 18;
  ZIP := 90210;
end; 
previous contents next