LogicGate

program LogicGates;

var
  Gate: string;
  FBit, SBit: integer;
  FBitBool, SBitBool: boolean;

begin
  FBit:= 2;
  SBit:= 2;
  while ((Gate<>'and') and (Gate<>'or') and (Gate<>'xor') and (Gate<>'nand')) do
        begin
        writeln('Enter logic gate: ');
        readln(Gate);
        Gate := lowercase(Gate);
        end;
  while ((FBit<0) or (FBit>1)) do
        begin
        writeln('Enter first input: ');
        readln(FBit);
        end;
  while ((SBit<0) or (SBit>1)) do
        begin
        writeln('Enter second input: ');
        readln(SBit);
        end;
  if (FBit=1) then
     FBitBool := true
  else
      FBitBool := false;
  if (SBit=1) then
     SBitBool := true
  else
      SBitBool := false;

  if (Gate='and') then
     begin
         if (FBitBool and SBitBool) then
            writeln('Result: 1')
         else
             writeln('Result: 0');
     end;
  if (Gate='or') then
     begin
         if (FBitBool or SBitBool) then
            writeln('Result: 1')
         else
             writeln('Result: 0');
     end;
  if (Gate='xor') then
     begin
          if (FBitBool xor SBitBool) then
            writeln('Result: 1')
          else
             writeln('Result: 0');
     end;
  if (Gate='nand') then
     begin
          if (FBitBool=false and SBitBool=false) then
            writeln('Result: 1')
          else
             writeln('Result: 0');
     end;
  readln();
end.