Apply suggestions from code review

Co-authored-by: Jeremie Vandenplas <jeremie.vandenplas@gmail.com>

Author: 0382

example/sorting/example_radix_sort.f90

@@ -4,7 +4,8 @@ program example_radix_sort
     implicit none
     integer(int8), allocatable :: arri8(:)
     integer(int16), allocatable :: arri16(:)
-    real(dp), allocatable, target :: arrf64(:), x
+    real(dp) ::  x
+    real(dp), allocatable ::  arrf64(:)
 
     arri8 = [-128, 127, 0, -1, 1]
     call radix_sort(arri8)
@@ -19,7 +20,7 @@ program example_radix_sort
     arrf64 = [1.0_dp/x, 0.0_dp, 0.0_dp/x, -1.0_dp/x, -0.0_dp, 1.0_dp, -1.0_dp, 3.45_dp, -3.14_dp, 3.44_dp]
     call radix_sort(arrf64)
     print *, arrf64
-    ! In my computer, it gives
+    ! Expect output:
     ! nan, -inf, -3.14, -1.0, -0.0, 0.0, 1.0, 3.44, 3.45, inf
-    ! but the position of nan is undefined, the position of `±inf`, `±0.0` is as expected
+    ! Note: the position of nan is undefined
 end program example_radix_sort

src/stdlib_sorting_radix_sort.f90

@@ -235,8 +235,8 @@ pure module subroutine int16_radix_sort(array, work, reverse)
         end if
         call radix_sort_u16_helper(N, array, buffer)
 ! After calling `radix_sort_u<width>_helper. The array is sorted as unsigned integers.
-! In the view of signed arrsy, the negative numbers are sorted but in the tail of the array.
-! Use binary search to find the boundary, and move then to correct position.
+! In the view of signed array, the negative numbers are sorted but in the tail of the array.
+! Use binary search to find the boundary, and move them to correct position.
         if (array(1) >= 0 .and. array(N) < 0) then
             start = 1
             end = N