一个fortran文件

好的，以下是一个简单的Fortran文件的示例，它实现了一个计算器功能，可以让用户输入两个数字并执行四则运算：

program calculator

  implicit none

  integer :: num1, num2, result
  character :: operation

  write(*,*) "Welcome to the calculator program!"
  write(*,*) "Please enter the first number:"
  read(*,*) num1
  write(*,*) "Please enter the second number:"
  read(*,*) num2
  write(*,*) "Please enter the operation you would like to perform (+, -, *, /):"
  read(*,*) operation

  select case (operation)
  case '+'
    result = num1 + num2
  case '-'
    result = num1 - num2
  case '*'
    result = num1 * num2
  case '/'
    result = num1 / num2
  case default
    write(*,*) "Invalid operation entered."
    stop
  end select

  write(*,*) "The result of the operation is:", result

end program calculator

请注意，这只是一个简单的示例，实际上Fortran文件可以包含数千行代码，具体取决于程序的需求和复杂性。