If-else usage in Lazarus

Question

I'm new to Lazarus and today I faced an issue with if-else usage. Everything is ok while there is only an if statement but when I'm trying to write an if-else statement this error shows up:

unit1.pas(48, 3) Fatal: Syntax error, ";" expected but "Else" found

I'm not sure if I need to wrap code inside the statements with begin end, but this FreePascal wiki page shows it like this

My code:

unit Unit1;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls, Math;

type

  { TForm1 }

  TForm1 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    Edit2: TEdit;
    Edit3: TEdit;
    Label1: TLabel;
    procedure Button1Click(Sender: TObject);
  private

  public

  end;

var
  Form1: TForm1;

implementation

{$R *.lfm}

{ TForm1 }

procedure TForm1.Button1Click(Sender: TObject);
var
  a, b, c, d, x, x1, x2:real;
begin
  a := strToFloat(Edit1.Text);
  b := strToFloat(Edit2.Text);
  c := strToFloat(Edit3.Text);
  d := Power(b, 2) - 4 * a * c;
  if d > 0 then
    x1 := (-b + sqrt(d))/(2 * a);
    x2 := (-b - sqrt(d))/(2 * a);
    Label1.Caption := 'x1 = ' + floatToStr(x1) + #10 + 'x2 = ' + floaTToStr(x2)
  else
    if d < 0 then
      Label1.Caption := 'Розв*язків немає';
    else
      x1 := (-b + sqrt(d))/(2 * a);
      Label1.Caption := 'x = ' + floatToStr(x);
end.

Answer 1

You seem to be trying to use indentation to group code under statements. Pascal doesn't use indentation for nesting code (I'm honestly unsure what its called). You need to use begin and then afterwards end.

Meaning you code should look as follows:

  if d > 0 then
  begin
    // All 3 lines below will run if "d > 0"
    x1 := (-b + sqrt(d)) / (2 * a);
    x2 := (-b - sqrt(d)) / (2 * a);
    Label1.Caption := 'x1 = ' + floatToStr(x1) + #10 + 'x2 = ' + floatToStr(x2);
  end // Do not ";" since the if statement is not over yet
  else if d < 0 then
  begin
    Label1.Caption := 'Розв*язків немає';
  end // Do not ";" since the if statement is not over yet
  else
  begin
    x1 := (-b + sqrt(d)) / (2 * a);
    Label1.Caption := 'x = ' + floatToStr(x);
  end; // End of the if statment