構造体の初歩

program ex01

  implicit none

! 構造体 bunsuuの定義

  type :: bunsuu

    integer :: bunsi, bunbo

  end type bunsuu

! bunsuu型の変数a,b,cの宣言

  type (bunsuu) :: a,b,c

  a=bunsuu(1,2)

  b=bunsuu(1,3)

  c%bunbo=a%bunbo*b%bunbo

  c%bunsi=a%bunsi*b%bunbo+b%bunsi*a%bunbo

!

! 解説

!

! a=a1/a2, b=b1/b2のとき，

!

!         a1   b1   a1*b2 + b1*a2

! c=a+b = -- + -- = -------------

!         a2   b2       a2*b2

!

! 結果の出力

  write(*,*)a%bunsi,'/',a%bunbo,'+'

  write(*,*)b%bunsi,'/',b%bunbo,'='

  write(*,*)c%bunsi,'/',c%bunbo

  stop

end program ex01

$ ex01

           1 /           2 +

           1 /           3 =

           5 /           6

program ex02

!

! 構造体を扱うサブルーチンと関数の例

!  分数の入出力を行うサブルーチン

!  分数の和を計算する関数

!

  implicit none

! 構造体 bunsuuの定義

  type :: bunsuu

    integer :: bunsi, bunbo

  end type bunsuu

! bunsuu型の変数a,b,cの宣言

  type (bunsuu) :: a,b,c,d,e,f

! 分数a,b,cを読み込む

  call yomu('a=',a)

  call yomu('b=',b)

  call yomu('c=',c)

  d=wa(a,b)

  e=wa(c,d)

  f=wa(wa(a,b),c)

  call kaku('a+b = ',d)

  call kaku('c+d = ',e)

  call kaku('a+b+c = ',f)

  stop

contains !以下では構造体bunsuuが使える

!分数の足し算を行う関数

  function  wa(a,b)

    implicit none

    type (bunsuu) :: wa

    type (bunsuu), intent(in) :: a,b

!   waの分子の計算

    wa%bunsi=a%bunsi*b%bunbo+b%bunsi*a%bunbo

!   waの分母の計算

    wa%bunbo=a%bunbo*b%bunbo

   return

  end function wa

! 分数の読み込みを行うサブルーチン

  subroutine yomu(ji,a)

    implicit none

    character(*), intent(in) :: ji

    type (bunsuu), intent(out) :: a

    write(*,*)ji

    read(*,*) a%bunsi, a%bunbo

    return

  end subroutine yomu

! 分数の書き出しを行うサブルーチン

  subroutine kaku(ji,a)

    implicit none

    character(*), intent(in) :: ji

    type (bunsuu), intent(in) :: a

    character(14) :: fmt='(1x,a,i3,a,i3)'

    write(*,fmt)ji,a%bunsi,'  /',a%bunbo

    return

  end subroutine kaku

end program ex02

$ ex02

 a=

1,2

 b=

1,3

 c=

1,6

 a+b =   5  /  6

 c+d =  36  / 36

 a+b+c =  36  / 36

!

! 配列を構成要素にもつ構造体の例

!

module lorenz

  private

  integer, public, parameter :: ndim1=2,ndim2=3

! 構造体systemの定義

  type, public :: system

!   構成要素はx1とx2

    real,dimension (ndim1) :: x1

    real,dimension (ndim2) :: x2

  end type system

end module lorenz

program ex03

  use lorenz

  implicit none

! 派生型の変数aを宣言（構成要素は配列x1とx2）

  type (system) :: a

  a%x1(1)=1

  a%x1(2)=2

  a%x2(1)=11

  a%x2(2)=12

  a%x2(3)=13

  write(*,*)'a%x1'

  write(*,*)a%x1

  write(*,*)'a%x2'

  write(*,*)a%x2

  write(*,*)'a'

  write(*,*)a

end program ex03

$ ex03

 a%x1

   1.00000000000000        2.00000000000000    

 a%x2

   11.0000000000000        12.0000000000000        13.0000000000000    

 a

   1.00000000000000        2.00000000000000        11.0000000000000    

   12.0000000000000        13.0000000000000  

!

! 配列を構成要素にもつ構造体の例

! 派生型が配列になる例

!

module lorenz

  private

  integer, public, parameter :: ndim1=2,ndim2=3

! 構造体systemの定義

  type, public :: system

!   構成要素はx1とx2

    real,dimension (ndim1) :: x1

    real,dimension (ndim2) :: x2

  end type system

end module lorenz

program ex04

  use lorenz

  implicit none

! 派生型の配列aを宣言（構成要素は配列x1とx2）

  type (system) :: a(2)

  integer i

  a(1)%x1(1)=1

  a(1)%x1(2)=2

  a(1)%x2(1)=11

  a(1)%x2(2)=12

  a(1)%x2(3)=13

  a(2)%x1(1)=21

  a(2)%x1(2)=22

  a(2)%x2(1)=31

  a(2)%x2(2)=32

  a(2)%x2(3)=33

  do i=1,2

    write(*,*)'i=',i

    write(*,*)'a(i)%x1'

    write(*,*)a(i)%x1

    write(*,*)'a(i)%x2'

    write(*,*)a(i)%x2

    write(*,*)'a(i)'

    write(*,*)a(i)

    write(*,*)

  enddo !i

end program ex04

$ ex04

 i=           1

 a(i)%x1

   1.00000000000000        2.00000000000000    

 a(i)%x2

   11.0000000000000        12.0000000000000        13.0000000000000    

 a(i)

   1.00000000000000        2.00000000000000        11.0000000000000    

   12.0000000000000        13.0000000000000    

 i=           2

 a(i)%x1

   21.0000000000000        22.0000000000000    

 a(i)%x2

   31.0000000000000        32.0000000000000        33.0000000000000    

 a(i)

   21.0000000000000        22.0000000000000        31.0000000000000    

   32.0000000000000        33.0000000000000