Programmer

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Programmers Guide to F

• Structures and Derived Datatypes

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Structures and Derived Datatypes

• 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.

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Structures and Derived Datatypes

• Derived types are used to define the form of the
  structures.

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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.

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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.
• statement1
• statement2
• statement3

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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.

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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.

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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.

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6.1 Structures
name

• The name of the structure is person.
• It has 4 components name, address, phone, and
  remarks.

address
person
phone
remarks
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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.

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6.2 Derived Types

• As we discussed before, there are 5 intrinsic F
  data types
• integer
• real
• complex
• logical
• character

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6.2 Derived Types

• A programmer may define a new data type, called a
  derived type.

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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.

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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.

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6.2 Derived Types

• Lets 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)

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6.2 Derived Types

• Lets 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.

area_ code
phone_ type
number
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6.2 Derived Types

• type, public phone_type
• integer area_code, number
• end type phone_type

area_ code
phone
number
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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.

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6.2 Derived Types
number
street

• type, public address_type
• integer number
• character (len30) street, city
• character (len2) state
• integer zip_code
• end type address_type

city
address
state
zip_code
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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.

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6.2 Derived Types

• type, public person_type
• character (len40) name
• type (address_type) address
• type (phone_type) phone
• character (len100) remarks
• end type person_type

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6.2 Derived Types

• type, public person
• character(len12) first_name
• character(len1) middle_initial
• character(len12) last_name
• integer age
• character(len1) sex ! M or F
• character(len5) tax_number
• end type person

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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

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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

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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)

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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

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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).

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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

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6.3.1 Referencing Structure Components

• Suppose joan is an f variable declared to be type
  person_type. Then Joans address is referenced by
  the expression
• joan address
• The object joanaddress 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

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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.

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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)

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6.3.2 Structure Constructors

• It is not necessary that the function arguments
  be constants. If joanaddress 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, johnaddress,
• phone_type (505, fax_number 1),
• Same address as husband John)

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• type, public employee type(person)
  employee character(len20) department real
  salaryend type employee
• type(person) saadet
• saadetemployeeage 34

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

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Putting data in a derived type variable

• ali person("Ali","M","Aktepe",56,"M","45645")
• mukaddes person("Mukaddes"," ","Has",18,"F","1234
  5")
• veli person("Veli","M","Karatepe",65,"M","34567"
  )
• This is a structure constructor

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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.
topgerceks1gercek s2gercek topsanal
s1sanal s2sanal farkgerceks1gercek-
s2gercek farksanal s1sanal - s2sanal
carpimgercek s1gerceks2gercek -
s1sanals2sanal carpimsanal
s1gerceks2sanal s1sanals2gercek
print ,"s1s2", top print ,"s1-s2", fark
print ,"s1s2", carpim end program ornek
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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 -2.0mx d -2my e (mx)2
(my)2 - (rds(p,m))2 print , "Cember
denkleminin," print , "ax2by2cxdye0
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 (px - mx)2
g2 (py - my)2 r sqrt(g1 g2) end
function rds end module m1
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program e_8_4 use m1 type(aile), dimension(4)
diaz integer i do i1,4 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)ksslad))//" "//
trim(adjustl(diaz(i)ksslsad))//"."
print , diaz(i)ksslyas,"yasindasiniz
cinsiyetniz ",diaz(i)ksslcins, "
ve mesleginiz ",diaz(i)ksslmeslek,"." end do
print , "Adresiniz" print ,
trim(adjustl(diaz(i)addrgenel)) print ,
diaz(i)addrsemt print , diaz(i)addril
print , diaz(i)addrulke end program e_8_4
module m1 type, public kibil character
(len20) ad, sad character (len1) cins
! E,K integer yas character
(len20) meslek end type kibil type,
public adres character (len100) genel
character (len20) semt, il, ulke end type
adres type, public aile type(kibil)
kssl type(adres) addr end type aile end
module m1