Combo Master (Combinations finder)

{A program that can find all combinations possible with n integer}
Program exercice;
uses wincrt;
Var
f:text;
n:integer;

procedure creation (var f:text);
Begin
    assign (f,'c:\bac\combianaison.txt');
end;
procedure saisie (var n:integer);
Begin
    Repeat
        write ('Saisir N: ');
        readln (n);
    Until n in [1..100] ;
end;
function nettoyage (ch:string):string;
Begin
    while (ch[1]='0') Do
        Begin
            delete (ch,1,1);
        end;
    nettoyage:=ch;
end;
procedure traitement (var f:text;n:integer);
Var
ch,ch1,c:string;
aux:char;
i:integer;
Begin
    ch:='';
    for i:=n-1 downto 0 Do
        Begin
            str (i,c);
            ch:=ch+c;
        end;
    ch1:=ch;
    rewrite (f);
    i:=0;
    Repeat
        i:=i+1;
        aux:=ch1[i];
        ch1[i]:=ch1[i+1];
        ch1[i+1]:=aux;
        writeln (f,nettoyage (ch1));
        if (i+1=Length(ch)) Then
            i:=0;
    Until (ch1=ch);
    close (f);
end;
procedure affiche (var f:text);
Var
ch:string;
Begin
    reset (f);
    while not (eof(f)) Do
        Begin
            readln (f,ch);
            writeln (ch);
        end;
    close (f);
end;
Begin
    creation (f);
    saisie (n);
    traitement (f,n);
    affiche (f);
end.