加减程序段

//加法过程
procedure plus(var a1,b1:arr;var x:arr);
  var i,k:integer;
  begin
    k:=0;
    for i:=1 to l do
      begin
        a1[i]:=a1[i]+b1[i]+k;
        k:=a1[i] div 10;
        a1[i]:=a1[i] mod 10;
      end;
    if k>0 then begin inc(l);a[l]:=k;end;
    x:=a1;
 end;

//加法函数
function plus(a,b:arr):arr;
  var i,c:integer;
  begin
    c:=0;
    for i:=1 to l do
      begin
        a[i]:=a[i]+b[i]+c;
        c:=a[i] div 10;
        a[i]:=a[i] mod 10;
      end;
    if c>0 then begin inc(l);a[l]:=c;end;
    plus:=a;
  end;
//减法过程
procedure minus(var a:numtype;var la:integer;b:numtype);    {计算a=a-b,返回差a及其长度la}
var
 i:integer;
begin
 for i:=1 to la do                            {逐位相减}
  begin
   if a[i]<b[i]                                {借位}
     then begin dec(a[i+1]);a[i] :=a[i]+10;end;
   a[i] :=a[i]-b[i];                            {计算差的第i位}
  end;
  while a[la]=0 do dec(la);                            {计算差的实际长度}
 end;