how to decifer from prime or not prime numbers

[chickenmcnugget]

hello there im sorry i can not help you with your problem and like i said i am very sorry i am looking for some help myself first i do not know how to post a question on here second i need help with a program it is in pascal and i need it to decifer from prime or not prime between the numbers 1 and 1000 so plz ne who reads this help i know pascal but im in college so its their thing ne one plz help me thanx again.

[voken]

procedure TForm1.Button1Click(Sender: TObject);
  Function is_prime(r:integer):boolean;
  var j:integer;
  begin
     if (r=1) or (r=2) then begin result:=true;  exit; end;
       for j := 2 to r-1 do begin
        if (r mod j=0) then begin   
           result:=false;//not prime
           exit;
        end;   
      end; 
      result := true;//prime
   end;  

var j,r,k,a,b,c:integer;
    red:boolean;

begin
     listbox1.Clear ;
     listbox2.Clear ;
     listbox3.Clear ;
  {start value}      i:=strtoint(combobox1.Text );
{end value}  j:= strtoint(combobox2.Text);
     for i:=i to j do
       begin
    if (i mod 2=0) then
        listbox1.Items.Add(inttostr(i))
       else
            listbox2.Items.Add(inttostr(i));
       if is_prime(i) then listbox3.Items.Add(inttostr(i));
     end;
 end;

[voken]

procedure TForm1.Button1Click(Sender: TObject);
  Function is_prime(r:integer):boolean;
  var j:integer;
  begin
     if (r=1) or (r=2) then begin result:=true;  exit; end;
       for j := 2 to r-1 do begin
        if (r mod j=0) then begin   
           result:=false;//not prime
           exit;
        end;   
      end; 
      result := true;//prime
   end;  

var j,r,k,a,b,c:integer;
    red:boolean;

begin
     listbox1.Clear ;
     listbox2.Clear ;
     listbox3.Clear ;
  {start value}      i:=strtoint(combobox1.Text );
{end value}  j:= strtoint(combobox2.Text);
     for i:=i to j do
       begin
    if (i mod 2=0) then
        listbox1.Items.Add(inttostr(i))
       else
            listbox2.Items.Add(inttostr(i));
       if is_prime(i) then listbox3.Items.Add(inttostr(i));
     end;
 end;

[FlamingClaw]

http://www.daniweb.com/code/snippet217321.html

[wylddev]

try this function below and see if it works..

function IsPrime(const n: int64): boolean;
var
i: cardinal;
en: extended;
begin
if n <> 2 then begin
en := n;
for i := 2 to round(sqrt(en)) do
if n mod i = 0 then begin
result := false;
exit;
end;
end;
result := n > 0; // or > 1
end;