1. Programmer’s Guide to F Structures and Derived Datatypes

2. Arrays allow data to be grouped, but only if all items have the same data type. It is often useful to use a structure, which is a compound object consisting of values that may be of different data types.

3. Structures and Derived Datatypes Derived types are used to define the form of the structures.

4. 6.1 Structures A structure is a collection of values, not necessarily of the same type. The objects that make up a structure are called its components.

5. 6.1 Structures A good example of the use of a structure might be provided by a simple list, consisting of line numbers and statements on each line. 1 statement1 2 statement2 3 statement3::

6. 6.1 Structures This list can be represented as 2 arrays, one to hold line numbers and one to hold the text of each line.

7. 6.1 Structures Perhaps, a better way to do this is to have a single object called line consisting of two components, an integer line_number and a character string statement. The entire list would then be an array of these structures, one for each line.

8. 6.1 Structures A slightly more complicated example: Suppose we wish to store in our computer the contents of our little black book that contains names, addresses, phone numbers, and some remarks about each person.

9. 6.1 Structures The name of the structure is person. It has 4 components: name, address, phone, and remarks. person name address phone remarks

10. 6.1 Structures Sometimes the components might be broken down into lower-level components. For instance, the address itself could be a structure with components number, street, city, state, and postal zip_code.

11. 6.2 Derived Types As we discussed before, there are 5 intrinsic F data types: integer real complex logical character

12. 6.2 Derived Types A programmer may define a new data type, called a derived type.

13. 6.2 Derived Types A type definition begins with the keyword type, followed by either private or public accessibility attribute, followed by two colons (::) and the name of the type being defined.

14. 6.2 Derived Types The components of the type are given in the ordinary type declarations. The type definition ends with the keywords end type, followed by the name of the type being defined. All type definitions must be put in a module.

15. 6.2 Derived Types Let’s start with our first example, a list containing line numbers and statements. type, public :: line integer :: line_number character (len = line_length) :: text end type line where line_length is an integer parameter (named constant)

16. 6.2 Derived Types Let’s return to the example of the little black book. To define the type phone_type in that example, area_code and number are each declared to be integer components. phone_ type area_ code number

17. 6.2 Derived Types type, public :: phone_type integer :: area_code, number end type phone_type phone area_ code number

18. 6.2 Derived Types The definition od the type address_type is a little more complicated because some of the components are character strings and some are integers.

19. 6.2 Derived Types type, public :: address_type integer :: number character (len=30) :: street, city character (len=2) :: state integer :: zip_code end type address_type address number street city state zip_code

20. 6.2 Derived Types Now that, the types address_type and phone_type are defined, it is possible to define a type suitable for one entry in the black book. Note that the names address_type and phone_type were used for the names of the types, so that the names address and phone could be used for the components of the type person_type.

21. 6.2 Derived Types type, public :: person_type character (len=40) :: name type (address_type) :: address type (phone_type) :: phone character (len=100) :: remarks end type person_type

22. 6.2 Derived Types type, public :: person character(len=12) :: first_name character(len=1) :: middle_initial character(len=12) :: last_name integer :: age character(len=1) :: sex ! M or F character(len=5) :: tax_number end type person

23. 6.3 Declaring and Using Structures Given the type definition for line that can be used to hold a line number and one statement, a variable new_line that could be used to represent one line of the list that can be declared by type (line) :: new_line

24. 6.3 Declaring and Using Structures The entire list could be represented by a single variable declared to be an array of values of type line: type (line), dimension (max_lines) :: list

25. 6.3 Declaring and Using Structures For example, to print a line of the list: If two arrays were used print “(i5, tr1, a)”, line_number(n), text(n) With this declaration print “(i5, tr1, a)”, list(n)

26. 6.3 Declaring and Using Structures To use the type declarations for the address book, joan can be declared to be type person_type with the statement type (person_type) : joan and the little black book can be declared to be an array of type person_type: type (person_type), dimension (1000) :: black_book

27. 6.3 Declaring and Using Structures Any program or module that is to contain a derived type declaration must use the module containing the derived type definition (or be in the module).

28. 6.3.1 Referencing Structure Components A component of a structure is referenced by writing the name of the structure by a percent sign (%) and then the name of the component

29. 6.3.1 Referencing Structure Components Suppose joan is an f variable declared to be type person_type. Then Joan’s address is referenced by the expression joan % address The object joan%address is itself a structure. If it is desired to refer to one of the components of this structure, another percent symbol is used. joan % address % state and joan % phone % area_code

30. 6.3.2 Structure Constructors Each derived-type declaration creates a structure constructor, whose name is the same as that of the derived type. For example, if you define a type named boa, you have a boa constructor.

31. 6.3.2 Structure Constructors The arguments are values to be placed in the individual components of the structure. For example, using the type phone_type, an area code and telephone number may be assigned with the statement joan % phone = phone_type (505, 2750800)

32. 6.3.2 Structure Constructors It is not necessary that the function arguments be constants. If joan%address has been given a value, the variable joan of type person_type can be assigned a value with the statement joan = person_type (“Joan Doe”, john%address, & phone_type (505, fax_number – 1), & “Same address as husband John”)

33. type, public :: employee type(person) :: employee character(len=20) department real :: salary end type employee type(person) :: saadet saadet%employee%age = 34

34. Now you can declare variable of type person: type ( type­_name ) : : list_of_identifiers type(person) :: ali, mukaddes, veli

35. Putting data in a derived type variable ali = person("Ali","M","Aktepe",56,"M","45645") mukaddes =person("Mukaddes"," ","Has",18,"F","12345") veli = person("Veli","M","Karatepe",65,"M","34567") This is a structure constructor

36. module kompleks type, public :: kom real :: gercek, sanal end type kom end module kompleks program ornek use kompleks type(kom) :: s1, s2, top, fark, carpim print *, "Birinci kompleks sayiyi yaziniz." read *, s1 print *, "ikinci kompleks sayiyi yaziniz." read *, s2 !iki kompleks sayinin toplami. top%gercek=s1%gercek + s2%gercek top%sanal =s1%sanal + s2%sanal fark%gercek=s1%gercek- s2%gercek fark%sanal =s1%sanal - s2%sanal carpim%gercek= s1%gercek*s2%gercek - s1%sanal*s2%sanal carpim%sanal = s1%gercek*s2%sanal + s1%sanal*s2%gercek print *,"s1+s2=", top print *,"s1-s2=", fark print *,"s1*s2=", carpim end program ornek

37. program e_8_3 use m1 type(nokta) :: m,p real :: yaricap, a,b,c,d,e print *, "Cemberin merkezinin koordinatlarini ",& "girin (x,y)." read *, m print *, "Cember uzerindeki bir noktanin ", & "koordinatlarini girin (x,y)." read *, p print *, " " print *, "Cemberin yaricapi", rds(p,m),"dir." print *, " " a = 1.0 b = 1.0 c = -2.0*m%x d = -2*m%y e = (m%x)**2 + (m%y)**2 - (rds(p,m))**2 print *, "Cember denkleminin," print *, "ax2+by2+cx+dy+e=0 formundaki katsayilari:" print *, "a=",a print *, "b=",b print *, "c=",c print *, "d=",d print *, "e=",e end program e_8_3 module m1 public :: rds type, public :: nokta real :: x, y end type nokta contains function rds(p,m) result(r) type(nokta), intent(in) :: p, m real :: r real :: g1, g2 ! Ara islemlerde kullanilan ! yerel/gecici degiskenler. g1 = (p%x - m%x)**2 g2 = (p%y - m%y)**2 r = sqrt(g1 + g2) end function rds end module m1

38. program e_8_4 use m1 type(aile), dimension(4) :: diaz integer :: i do i=1,4 print *, "Ad, soyad, cinsiyet(E,K), yas, meslek",& " bilgilerini giriniz." print *, "Adres bilgilerinizi girin.(genel, semt, il, ulke)" read *, diaz(i) print *, "Adiniz ",trim(adjustl(diaz(i)%kssl%ad))//" "// & trim(adjustl(diaz(i)%kssl%sad))//"." print *, diaz(i)%kssl%yas,"yasindasiniz cinsiyetniz ",diaz(i)%kssl%cins, & " ve mesleginiz ",diaz(i)%kssl%meslek,"." end do print *, "Adresiniz:" print *, trim(adjustl(diaz(i)%addr%genel)) print *, diaz(i)%addr%semt print *, diaz(i)%addr%il print *, diaz(i)%addr%ulke end program e_8_4 module m1 type, public ::kibil character (len=20) :: ad, sad character (len=1) :: cins ! E,K integer :: yas character (len=20) :: meslek end type kibil type, public :: adres character (len=100):: genel character (len=20) :: semt, il, ulke end type adres type, public :: aile type(kibil) :: kssl type(adres) :: addr end type aile end module m1