CS-460-1.Fall-2005:Homeworks:KellyBreedHomework

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Contents 1 HW 1 1.1 Last Element of a List 1.2 Stripped Down Tree 1.3 Capitalize First Character of a String 1.4 Average a List

[edit] HW 1

[edit] Last Element of a List

It's been pointed out to me that there is a builtin for this, but this is my story and I'm sticking to it.

% Returns the last element of a list

declare
fun {Last S}
   case S of H|T then
      if T == nil then H
      else {Last T}
      end
   end
end

local C N in
   C=['Scarecrow' 'Tinman' 'Cowardly Lion']
   {Browse {Last C}}

   N=[4 6 3 4 8 9 7 6 54 21]
   {Browse {Last N}}
end

[edit] Stripped Down Tree

%An extremely simple tree insertion procedure

local T T1 T2 T3 T4 Value TreeIn TreeOut Insert in

   proc {Insert Value TreeIn TreeOut}
      case TreeIn
	 of nil then TreeOut = tree(Value nil nil) 
      []  tree(V Ti To) then
	 if Value < V then Tmp in
	    TreeOut = tree(V Tmp To)
	    {Insert Value Ti Tmp}
	 else Tmp in
	    TreeOut = tree(V Ti Tmp)
	    {Insert Value Ti Tmp}
	 end
	 end
   end
   T = nil
   {Insert 7 T T1}
   {Insert 9 T1 T2}
   {Browse T2}
end

[edit] Capitalize First Character of a String

% Capitalizes the first character of a string.

local S O CapFirst StringIn StringOut in

   proc {CapFirst StringIn StringOut}
      local H T O in
	 StringIn = H|T
	 {Char.toUpper H O}
	 StringOut = O|T
      end
   end

   S = "this is an uncapitalized sentence."
   {CapFirst S O}
   {Browse O}
end

[edit] Average a List

% Gives average of a list of floats
local A B Average ListIn Out C L LF in
   proc {Average ListIn Out}
      L = {Length ListIn}
      LF = {IntToFloat L}
      {NewCell 0.0 C}
      for X in ListIn do C:=@C+X end
      Out = @C/LF
   end
   
   A = [3.0 2.0]
   {Average A B}
   {Browse B}
end

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