Question

How to increment an integer represented as an integer array of digits by one in Pascal

Answer 1

program IncrementArray;

const
  MaxSize = 64;

type
  IntArray = array[1..MaxSize] of Integer;

procedure IncrementByOne(var digits: IntArray; var size: Integer);
var
  i, carry: Integer;
begin
  carry := 1;
  for i := size downto 1 do
  begin
    digits[i] := digits[i] + carry;
    if digits[i] = 10 then
    begin
      digits[i] := 0;
      carry := 1;
    end
    else
    begin
      carry := 0;
      Break;
    end;
  end;

  if carry = 1 then
  begin
    // Shift all elements to the right
    for i := size downto 1 do
      digits[i + 1] := digits[i];
    digits[1] := 1;
    Inc(size);
  end;
end;

var
  digits: IntArray;
  size, i: Integer;

begin
  // Initialize the array with {9, 9, 9}
  size := 3;
  digits[1] := 9;
  digits[2] := 9;
  digits[3] := 9;

  IncrementByOne(digits, size);

  Write('Result: ');
  for i := 1 to size do
    Write(digits[i], ' ');
  Writeln;
end.



(*
run:

Result: 1 0 0 0 

*)

 

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