Free pascal database tutorial5/2/2023 ![]() Writeln( 'Book 2 subject : ', Book2^.subject) Writeln('Book 2 author : ', Book2^.author) Writeln ('Book 2 title : ', Book2^.title) Writeln( 'Book 1 book_id : ', Book1^.book_id) Writeln( 'Book 1 subject : ', Book1^.subject) Writeln('Book 1 author : ', Book1^.author) Writeln ('Book 1 title : ', Book1^.title) (* Declare Book1 and Book2 of pointer type that refers to Book type *)īook1^.subject := 'C Programming Tutorial' īook2^.subject := 'Telecom Billing Tutorial' ![]() Hope this will be easy for you to understand the concept − Let us re-write the first example using a pointer to the Books record. operator as follows −įinally, don't forget to dispose the used storage, when it is no longer in use − To access the members of a record using a pointer to that record, you must use the ^. To declare a variable of the created pointer type, you use the var keyword −īefore using these pointers, you must create storage for a record-name type variable, which will be manipulated by these pointers. Now, you can store the address of a record type variable in the above-defined pointer variable. You can define pointers to records in very similar way as you define pointer to any other variable as follows − Writeln( 'Book book_id : ', book.book_id) Writeln( 'Book subject : ', book.subject) You would access the record fields in the similar way as you have accessed in the above example − You can pass a record as a subprogram argument in very similar way as you pass any other variable or pointer. When the above code is compiled and executed, it produces the following result −īook 2 subject : Telecom Billing Tutorial Writeln( 'Book 2 book_id : ', Book2.book_id) Writeln( 'Book 2 subject : ', Book2.subject) Writeln ('Book 2 title : ', Book2.title) Writeln( 'Book 1 book_id : ', Book1.book_id) Writeln( 'Book 1 subject : ', Book1.subject) Writeln ('Book 1 title : ', Book1.title) Following is the example to explain usage of structure −īook1, Book2: Books (* Declare Book1 and Book2 of type Books *)īook1.subject := 'C Programming Tutorial' īook2.subject := 'Telecom Billing Tutorial' ![]() The member access operator is coded as a period between the record variable name and the field that we wish to access. To access any field of a record, we use the member access operator (.). ![]() The record variables are defined in the usual way asĪlternatively, you can directly define a record type variable as − Here is the way you would declare the Book record − To define a record type, you may use the type declaration statement. Suppose you want to keep track of your books in a library, you might want to track the following attributes about each book − Pascal arrays allow you to define type of variables that can hold several data items of the same kind but a record is another user-defined data type available in Pascal which allows you to combine data items of different kinds. ![]()
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