17.1: Module Declaration

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The secondary source file or module must be formatted in a specific manner as follows:

module <name>
    <declarations>
contains
    <subroutine and/or function definitions>
end module <name>

For example, to declare a module named stats that includes a function to find the average of the numbers in an array, the following module declaration might be used.

module stats
! note, no global variables used in this module

contains

! *************************************************************
!  Simple function to find average of len values in an array.

real function average(array, len)
real, intent(in), dimension(1000) :: array
integer, intent(in) :: len
integer :: i
    real :: sum = 0.0
    
    do i = 1, len
        sum = sum + array(i)
    end do
    average = sum / real(len)
end function average

end module stats

This example assumes the real array contains len number of values up to a maximum of 1000 values.