Binary Subtraction

[Pa|2a|)oX]

This program took me a shorter time to make because I knew what I was doing now.

This uses ones and twos compliment to subtract digits, and as so is inherently only able to subtract a maximum of 7 bits (127 in decimal).

No shortcuts, and this one is relatively well error trapped, it will tell you if you overflowed, and if you entered a wrong answer of some sort. The binary input section is not error trapped, only 1s and 0s may be inputed or it will crash.

Thanks

code:

%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %Subtraction                % %Kostia Palanski            % %Mr. Wong                   % %Binary Subtraction Program % %Done: Feb. 20th 2005       % %%%%%%%%%%%%%%%%%%%%%%%%%%%%% %Graphics Settings View.Set ("graphics:400;400,position:bottom;left,nobuttonbar") drawfillbox (0, 0, maxx, maxy, black) colorback (black) color (yellow) %Variable Declaration var snum1, snum2 : string var lsnum1, lsnum2 : int var msnum1, msnum2 : string var streamin, streamout : int var osubput : string var queryn1, queryn2, query : string var neg1, neg2, neg : int := 0 var aosnum2 : array 1 .. 8 of int var aosnum1 : array 1 .. 8 of int var finalAnswer : array 1 .. 8 of int var finalAnswerint : int var oflow : int := 0 %TwosCompliment Variables var twoC : string := "00000001" var aotwoC : array 1 .. 8 of int for f : 1 .. 8     aotwoC (f) := strint (twoC (f)) end for %Ones Compliment for Num2 procedure onesComplimentNum2     for e : 1 .. 8         if aosnum2 (e) = 1 then             aosnum2 (e) := 0         elsif aosnum2 (e) = 0 then             aosnum2 (e) := 1         end if     end for end onesComplimentNum2 %Ones Compliment for Num1 procedure onesComplimentNum1     for e : 1 .. 8         if aosnum1 (e) = 1 then             aosnum1 (e) := 0         elsif aosnum1 (e) = 0 then             aosnum1 (e) := 1         end if     end for end onesComplimentNum1 %Ones Compliment for FinalAnswer procedure onesComplimentFA     for e : 1 .. 8         if finalAnswer (e) = 1 then             finalAnswer (e) := 0         elsif finalAnswer (e) = 0 then             finalAnswer (e) := 1         end if     end for end onesComplimentFA %Twos Compliment for aosnum1 procedure twosComplimentNum1     %%%%%%%%%%%%%%%%%%%%%%%%     var final : array 1 .. 8 of int     var fdigit : int := 0     var carry : int := 0     %%%%%%%%%%%%%%%%%%%%%%%%     for decreasing g : 8 .. 1         if g = 1 and aosnum1 (g) + aotwoC (g) = 0 and carry = 0 then             fdigit := 0         elsif g = 1 and aosnum1 (g) + aotwoC (g) = 1 and carry = 0 then             fdigit := 1         elsif g = 1 and aosnum1 (g) + aotwoC (g) = 1 and carry = 1 then             fdigit := 10         elsif g = 1 and aosnum1 (g) + aotwoC (g) = 2 and carry = 0 then             fdigit := 10         elsif g = 1 and aosnum1 (g) + aotwoC (g) = 2 and carry = 1 then             fdigit := 11         end if         %%%%%%%%%%%%%%%%%%%%%%%%         if aosnum1 (g) + aotwoC (g) = 0 and carry = 0 then             final (g) := 0             carry := 0         elsif aosnum1 (g) + aotwoC (g) = 0 and carry = 1 then             final (g) := 1             carry := 0         elsif aosnum1 (g) + aotwoC (g) = 1 and carry = 0 then             final (g) := 1             carry := 0         elsif aosnum1 (g) + aotwoC (g) = 1 and carry = 1 then             final (g) := 0             carry := 1         elsif aosnum1 (g) + aotwoC (g) = 2 and carry = 0 then             final (g) := 0             carry := 1         elsif aosnum1 (g) + aotwoC (g) = 2 and carry = 1 then             final (g) := 1             carry := 1         end if     end for     %Put output     open : streamout, "subput.txt", put     for h : 1 .. 8         put : streamout, final (h) ..     end for     close : streamout     %Get it to one variable     open : streamin, "subput.txt", get     get : streamin, osubput : *     close : streamin     %Reassign the new TwosCompliment to aosnum1     for i : 1 .. 8         aosnum1 (i) := strint (osubput (i))     end for end twosComplimentNum1 %Twos Compliment for aosnum2 procedure twosComplimentNum2     %%%%%%%%%%%%%%%%%%%%%%%%     var final : array 1 .. 8 of int     var fdigit : int := 0     var carry : int := 0     %%%%%%%%%%%%%%%%%%%%%%%%     for decreasing g : 8 .. 1         if g = 1 and aosnum2 (g) + aotwoC (g) = 0 and carry = 0 then             fdigit := 0         elsif g = 1 and aosnum2 (g) + aotwoC (g) = 1 and carry = 0 then             fdigit := 1         elsif g = 1 and aosnum2 (g) + aotwoC (g) = 1 and carry = 1 then             fdigit := 10         elsif g = 1 and aosnum2 (g) + aotwoC (g) = 2 and carry = 0 then             fdigit := 10         elsif g = 1 and aosnum2 (g) + aotwoC (g) = 2 and carry = 1 then             fdigit := 11         end if         %%%%%%%%%%%%%%%%%%%%%%%%         if aosnum2 (g) + aotwoC (g) = 0 and carry = 0 then             final (g) := 0             carry := 0         elsif aosnum2 (g) + aotwoC (g) = 0 and carry = 1 then             final (g) := 1             carry := 0         elsif aosnum2 (g) + aotwoC (g) = 1 and carry = 0 then             final (g) := 1             carry := 0         elsif aosnum2 (g) + aotwoC (g) = 1 and carry = 1 then             final (g) := 0             carry := 1         elsif aosnum2 (g) + aotwoC (g) = 2 and carry = 0 then             final (g) := 0             carry := 1         elsif aosnum2 (g) + aotwoC (g) = 2 and carry = 1 then             final (g) := 1             carry := 1         end if     end for     %Put output     open : streamout, "subput.txt", put     for h : 1 .. 8         put : streamout, final (h) ..     end for     close : streamout     %Get it to one variable     open : streamin, "subput.txt", get     get : streamin, osubput : *     close : streamin     %Reassign the new TwosCompliment to aosnum2     for i : 1 .. 8         aosnum2 (i) := strint (osubput (i))     end for end twosComplimentNum2 %Twos Compliment for finalAnswer procedure twosComplimentFA     %%%%%%%%%%%%%%%%%%%%%%%%     var final : array 1 .. 8 of int     var fdigit : int := 0     var carry : int := 0     %%%%%%%%%%%%%%%%%%%%%%%%     for decreasing g : 8 .. 1         if g = 1 and finalAnswer (g) + aotwoC (g) = 0 and carry = 0 then             fdigit := 0         elsif g = 1 and finalAnswer (g) + aotwoC (g) = 1 and carry = 0 then             fdigit := 1         elsif g = 1 and finalAnswer (g) + aotwoC (g) = 1 and carry = 1 then             fdigit := 10         elsif g = 1 and finalAnswer (g) + aotwoC (g) = 2 and carry = 0 then             fdigit := 10         elsif g = 1 and finalAnswer (g) + aotwoC (g) = 2 and carry = 1 then             fdigit := 11         end if         %%%%%%%%%%%%%%%%%%%%%%%%         if finalAnswer (g) + aotwoC (g) = 0 and carry = 0 then             final (g) := 0             carry := 0         elsif finalAnswer (g) + aotwoC (g) = 0 and carry = 1 then             final (g) := 1             carry := 0         elsif finalAnswer (g) + aotwoC (g) = 1 and carry = 0 then             final (g) := 1             carry := 0         elsif finalAnswer (g) + aotwoC (g) = 1 and carry = 1 then             final (g) := 0             carry := 1         elsif finalAnswer (g) + aotwoC (g) = 2 and carry = 0 then             final (g) := 0             carry := 1         elsif finalAnswer (g) + aotwoC (g) = 2 and carry = 1 then             final (g) := 1             carry := 1         end if     end for     %Put output     open : streamout, "subput.txt", put     for h : 1 .. 8         put : streamout, final (h) ..     end for     close : streamout     %Get it to one variable     open : streamin, "subput.txt", get     get : streamin, osubput : *     close : streamin     %Reassign the new TwosCompliment to aosnum1     for i : 1 .. 8         finalAnswer (i) := strint (osubput (i))     end for end twosComplimentFA %Subtraction Procedure using Addition procedure subtract     var final : array 1 .. 8 of int     var fdigit : int := 0     var carry : int := 0     %%%%%%%%%%%%%%%%%%%%%%%%     for decreasing j : 8 .. 1         if j = 1 and aosnum1 (j) + aosnum2 (j) = 0 and carry = 0 then             fdigit := 0         elsif j = 1 and aosnum1 (j) + aosnum2 (j) = 1 and carry = 0 then             fdigit := 1         elsif j = 1 and aosnum1 (j) + aosnum2 (j) = 1 and carry = 1 then             fdigit := 10         elsif j = 1 and aosnum1 (j) + aosnum2 (j) = 2 and carry = 0 then             fdigit := 10         elsif j = 1 and aosnum1 (j) + aosnum2 (j) = 2 and carry = 1 then             fdigit := 11         end if         %%%%         if aosnum1 (j) + aosnum2 (j) = 0 and carry = 0 then             final (j) := 0             carry := 0         elsif aosnum1 (j) + aosnum2 (j) = 0 and carry = 1 then             final (j) := 1             carry := 0         elsif aosnum1 (j) + aosnum2 (j) = 1 and carry = 0 then             final (j) := 1             carry := 0         elsif aosnum1 (j) + aosnum2 (j) = 1 and carry = 1 then             final (j) := 0             carry := 1         elsif aosnum1 (j) + aosnum2 (j) = 2 and carry = 0 then             final (j) := 0             carry := 1         elsif aosnum1 (j) + aosnum2 (j) = 2 and carry = 1 then             final (j) := 1             carry := 1         end if     end for     %Outputs data to text file     open : streamout, "subput.txt", put     for h : 1 .. 8         put : streamout, final (h) ..     end for     close : streamout     %Get it to one variable     open : streamin, "subput.txt", get     get : streamin, osubput : *     close : streamin     %Reassign the new TwosCompliment to finalAnswer     for i : 1 .. 8         finalAnswer (i) := strint (osubput (i))     end for end subtract %%%%%%%%%%%%%%%%%%%%%%%%% %Beginning of Program loop     %Set overflow to 0 for repeated attempts     oflow := 0     %Error trapping loops     loop         put "Is the first number negative? (y/n)"         get queryn1         if queryn1 = "Y" or queryn1 = "N" or queryn1 = "y" or                 queryn1 = "yes" or queryn1 = "no" or queryn1 = "n" then             exit         else             put "Wrong input, this is a yes or no question.."             delay (400)         end if     end loop     %%%     loop         put "Please enter the first binary number.."         get snum1         lsnum1 := length (snum1)         if lsnum1 > 7 then             put "Only 7 bits can be inputed.."         else             exit         end if     end loop     %%     loop         put "Is the second number negative? (y/n)"         get queryn2         if queryn2 = "Y" or queryn2 = "N" or queryn2 = "y" or                 queryn2 = "yes" or queryn2 = "no" or queryn2 = "n" then             exit         else             put "Wrong input, this is a yes or no question.."             delay (400)         end if     end loop     %%     loop         put "Please enter the binary number to subtract.."         get snum2         lsnum2 := length (snum2)         if lsnum2 > 7 then             put "Only 7 bits can be inputed.."         else             exit         end if     end loop     %Setting negative values for loops     if queryn1 = "y" or queryn1 = "yes" or queryn1 = "Yes" or queryn1 = "Y" then         neg1 := 1     end if     if queryn2 = "y" or queryn2 = "yes" or queryn2 = "Yes" or queryn2 = "Y" then         neg2 := 1     end if     %Variables     msnum1 := snum1     msnum2 := snum2     %%%%%%%%%     %Zero addition and array input for aosnum1     var difnum1 : int := 8 - lsnum1     for a : 1 .. difnum1         msnum1 := "0" + msnum1     end for     for b : 1 .. 8         aosnum1 (b) := strint (msnum1 (b))     end for     %%%%%%%%%%%%     %Zero addition and array input aosnum2     var difnum2 : int := 8 - lsnum2     for c : 1 .. difnum2         msnum2 := "0" + msnum2     end for     for d : 1 .. 8         aosnum2 (d) := strint (msnum2 (d))     end for     %%%%%%%%%%%%     %What to do if negatives occur     if neg1 = 1 then         onesComplimentNum1         twosComplimentNum1     end if     if neg2 = 0 then         onesComplimentNum2         twosComplimentNum2     end if     %Run Subtract Procedure     subtract     put ""     put ""     %Overflow error trapping     if aosnum1 (1) = 0 and aosnum2 (1) = 0 and finalAnswer (1) = 1 then         put "The subtraction resulted in an overflow..."         oflow := 1     elsif aosnum1 (1) = 1 and aosnum2 (1) = 1 and finalAnswer (1) = 0 then         put "The subtraction resulted in an overflow..."         oflow := 1     end if     %Ones and Twos compliment of output is negative     if finalAnswer (1) = 1 then         neg := 1         onesComplimentFA         twosComplimentFA     end if     %Proceed with answer only of overflow = 0     if oflow = 0 then         finalAnswerint := strint (osubput)         put "The subtraction of these two values produces.."         if neg = 1 then             put "-", finalAnswerint         elsif neg = 0 then             put finalAnswerint         end if     end if     put ""     put ""     %Another set of calculations?     put "Would you like to calculate another value?"     get query     if query = "y" or query = "yes" or query = "Yes" or query = "Y" then         delay (400)         cls     else         exit     end if end loop %End Program