program structs
    implicit none
    
    type :: person
        character(len=100) :: name
        integer :: age
    end type person

    ! Function to create a new person
    type(person) function newPerson(name) result(p)
        character(len=*), intent(in) :: name
        p%name = name
        p%age = 42
    end function newPerson
    
    ! Variables declaration
    type(person) :: p
    type(person), pointer :: pp
    
    ! Create and print new person records
    call printPerson(person('Bob', 20))
    call printPerson(person('Alice', 30))
    call printPerson(person('Fred', 0))
    
    ! Create and print a pointer to a new person
    pp => person('Ann', 40)
    call printPersonPtr(pp)

    ! Use constructor function to create and print new person
    pp => newPerson('Jon')
    call printPersonPtr(pp)
    
    ! Access struct fields and demonstrate mutability
    p = person('Sean', 50)
    print *, p%name
    pp => p
    print *, pp%age

    ! Modify the age field
    pp%age = 51
    print *, pp%age

    ! Anonymous struct example, useful for table-driven tests
    call printDog('Rex', .true.)

contains

    ! Subroutine to print person details
    subroutine printPerson(p)
        type(person), intent(in) :: p
        print *, p
    end subroutine printPerson

    ! Subroutine to print details of a person pointer
    subroutine printPersonPtr(pp)
        type(person), pointer :: pp
        print *, pp
    end subroutine printPersonPtr

    ! Subroutine to print dog details
    subroutine printDog(name, isGood)
        character(len=*), intent(in) :: name
        logical, intent(in) :: isGood
        type, bind(c) :: dog
            character(len=100) :: name
            logical :: isGood
        end type dog
        type(dog) :: d
        d%name = name
        d%isGood = isGood
        print *, d
    end subroutine printDog

end program structs