June 2018 Update

Task/String-case/Fortran/string-case-4.f

@@ -0,0 +1,76 @@
+module uplow
+   implicit none
+   character(len=26), parameter, private :: low  = "abcdefghijklmnopqrstuvwxyz"
+   character(len=26), parameter, private :: high = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+contains
+
+   function to_upper(s) result(t)
+      ! returns upper case of s
+      implicit none
+      character(len=*), intent(in) :: s
+      character(len=len(s))        :: t
+
+      character(len=1), save       :: convtable(0:255)
+      logical, save                :: first = .true.
+      integer                      :: i
+
+      if(first) then
+         do i=0,255
+            convtable(i) = char(i)
+         enddo
+         do i=1,len(low)
+            convtable(iachar(low(i:i))) = char(iachar(high(i:i)))
+         enddo
+         first = .false.
+      endif
+
+      t = s
+
+      do i=1,len_trim(s)
+         t(i:i) = convtable(iachar(s(i:i)))
+      enddo
+
+   end function to_upper
+
+   function to_lower(s) result(t)
+      ! returns lower case of s
+      implicit none
+      character(len=*), intent(in) :: s
+      character(len=len(s))        :: t
+
+      character(len=1), save :: convtable(0:255)
+      logical, save          :: first = .true.
+      integer                :: i
+
+      if(first) then
+         do i=0,255
+            convtable(i) = char(i)
+         enddo
+         do i = 1,len(low)
+            convtable(iachar(high(i:i))) = char(iachar(low(i:i)))
+         enddo
+         first = .false.
+      endif
+
+      t = s
+
+      do i=1,len_trim(s)
+         t(i:i) = convtable(iachar(s(i:i)))
+      enddo
+
+   end function to_lower
+
+
+end module uplow
+
+
+program doit
+   use uplow
+   character(len=40) :: s
+
+   s = "abcdxyz ZXYDCBA _!@"
+   print *,"original: ",'[',s,']'
+   print *,"to_upper: ",'[',to_upper(s),']'
+   print *,"to_lower: ",'[',to_lower(s),']'
+
+end program doit