Program Sortir pada PASCAL

Program output_pascal;
uses crt;
label z;
label l;
var textfile:text;
FileName, TFile : String;
a:array[1..15] of string;
i,j:integer;
x,v:char;
temp: string;

procedure input;
Begin
clrscr;
gotoxy(10,10);Write('Masukkan nama file '+
+'dengan alamat lengkap dari file: ');
readln(FileName);clrscr;
writeln('-------DATA MAHASISWA-----');
writeln('--------------------------');
writeln('KELAS NAMA NPM');
writeln('--------------------------');
writeln;
{A .txt file will be assigned to a text variable}
Assign(textfile, 'd:\input.TXT');
Reset(textfile); {'Reset(x)' - means open the file x}
Repeat
Readln(textfile,TFile);
Writeln(TFile);
Until Eof(textfile);
Close(textfile);
Readln;
End;

procedure sort;
begin
clrscr;
assign(textfile,'d:\input.TXT');
reset(textfile);
for i:=1 to 15 do readln(textfile,a[i]);
close(textfile);



for i:=1 to 14 do
for j:=i to 15 do
if a[j] begin
temp:=a[i];
a[i]:=a[j];
a[j]:=temp;
end;end;

assign(textfile,'d:\input.TXT');
rewrite(textfile);
for i:=1 to 15 do writeln(textfile,a[i]);
close(textfile);
end;


procedure output;
Begin
clrscr;
gotoxy(4,5);Write('Masukkan nama file ');
gotoxy(4,6);write('(dengan alamat file lengkap) of the text file: ');
readln(FileName);
gotoxy(10,8);write('-------DATA MAHASISWA-----');
gotoxy(10,9);write('--------------------------');
gotoxy(10,10);write('KELAS NAMA NPM');
gotoxy(10,11);write('--------------------------');
{A .txt file will be assigned to a text variable}
Assign(textfile, 'd:\input.txt');
Reset(textfile); {'Reset(x)' - means open the file x}
Repeat
Readln(textfile,TFile);
Writeln(TFile);
Until Eof(textfile);
Close(textfile);
Readln;
End;

begin
z: clrscr;
gotoxy(20,8);write('-----------------------');
gotoxy(20,9);write('| Program Sorting |');
gotoxy(20,10);write('-----------------------');
gotoxy(20,11);write('|1.Masukkan Data |');
gotoxy(20,12);write('|2.Sortir Data |');
gotoxy(20,13);write('|3.Output |');
gotoxy(20,14);write('|4.Exit Menu |');
gotoxy(20,15);write(' Masukkan (1,2,3,4) : ');readln(x);

case x of
'1' : input;
'2' : sort;
'3' : output;
'4' : goto l;
end;

if x = '2' then
begin
clrscr;
writeln('Selesai(tekan Enter)');
writeln('this wait...'); readln;
goto z;
end;
writeln('Apakah anda ingin kembali ke menu? :{y/t} '); readln(v);
if (v = 'y') or (v = 'Y') then goto z;

l: end.