Add Insertion Sort in Fortran (#5244)

Author: leoraggy

archive/f/fortran/insertion-sort.f95

@@ -0,0 +1,74 @@
+program insertionsort
+    implicit none
+    character(len=256) input1
+    character(len=256) output
+    character(len=10) :: integer_number
+    integer, allocatable :: numbers(:)
+    integer :: i
+    
+    if(command_argument_count() /= 1) call usage()
+    call get_command_argument(1, input1)
+    if(input1 == "") call usage()
+    call convert_to_array(input1, numbers)
+    
+    if(size(numbers) == 1) call usage()
+    
+    call insertion_sort(numbers)
+    
+    output = ""
+    do i = 1, size(numbers)
+        write(integer_number, '(I0)') numbers(i)
+        if(len_trim(output) == 0) then
+            output = trim(integer_number)
+        else
+            output = trim(output) // ", " // trim(integer_number)
+        end if
+    end do
+    print '(A)', trim(output)
+    
+    
+contains
+    subroutine usage()
+        write(*,'(a)') 'Usage: please provide a list of at least two integers to sort in the format "1, 2, 3, 4, 5"'
+        stop
+    end subroutine usage
+    
+    subroutine convert_to_array(input1, numbers)
+        implicit none
+        character(len=*), intent(in) :: input1
+        integer, allocatable, intent(out) :: numbers(:)
+        integer :: i, length, pos, io_status
+        
+        length = 1
+        do i = 1, len_trim(input1)
+            if (input1(i:i) == ',') length = length + 1
+        end do
+    
+        allocate(numbers(length))
+    
+        pos = 1
+        do i = 1, length
+            read(input1(pos:), *, iostat=io_status) numbers(i)
+            if (io_status /= 0) call usage()
+            pos = index(input1(pos:), ',') + pos
+        end do
+    end subroutine convert_to_array
+    
+    subroutine insertion_sort(numbers)
+        implicit none
+        integer, intent(inout) :: numbers(:)
+        integer :: i, j, temp
+        
+        do i = 2, size(numbers)
+            temp = numbers(i)
+            j = i - 1
+            
+            do while (j >= 0 .and. numbers(j) > temp)
+                numbers(j+1) = numbers(j)
+                j = j - 1
+            end do
+            numbers(j+1) = temp
+        end do
+        
+    end subroutine insertion_sort
+end program insertionsort