Is it possible for a compiler to be ISO 7185 Pascal compliant and Borland Delphi compliant as well?

GNU GPC is such a compiler. It will take switches that configure it for either ISO 7185 use or Borland use. Note that several of the differences between the languages are compatible between the languages without the need for an option. Here is a list of ISO 7185 to Delphi differences, and whether they require a configuration option, and why. See the section "Differences between the languages", for details on each difference.

1. Procedure and function parameters.

Requires a configuration option: No

Reason: In delphi mode, the keyword procedure or function in a procedure or function header is an error. In ISO 7185 Pascal, it introduces a procedure or function parameter. This makes it essentially an extension to Delphi.

2. Interprocedural gotos.

Requires a configuration option: No

Reason: Such gotos cause an error in Delphi, so it behaves as simple extension.

3. File buffer access, "get" and "put" procedures.

Requires a configuration option: No

Reason: There are no get or put procedures in Delphi, and access to a file variable is illegal, so both of these act as simple extensions.

4. Sized variant record allocation.

Requires a configuration option: No

Reason: Allocating a variant record with new with Delphi is illegal, so it behaves as a simple extension.

5. "pack" and "unpack" functions.

Requires a configuration option: No

Reason: There are no pack or unpack procedures in Delphi, so it behaves as a simple extension. Note that in most cases, pack and unpack don't need to actually do anything, since arrays are allocated to the nearest byte on most microprocessors.

6. { and (*, } and *) are not synonyms.

Requires a configuration option: Yes

Reason: There is no way to have a single behavior that covers both the ISO 7185 and Delphi definition of how comments work.

7. Requires compiler directives to make a standard program.

Requires a configuration option: No

Reason: The compiler can simply ignore this comment.

8. End of line returns ASCII codes.

Requires a configuration option: Yes (or a different runtime library)

Reason: There is no way to satisfy both program standards. An eoln is either a space or the underlying ASCII characters.

9. Default field widths.

Requires a configuration option: Yes (or a different runtime library)

Reason: The basic behavior of the compiler must be changed.

So of the 9 basic differences between the standards, 3 of them are mutually incompatible between the two languages, and require options to change the basic workings of the compiler. The 6 remaining differences that are simply additions to the Delphi language can also be thought of as "freebies" that can be added to any Delphi compatible compiler in order to enable it to be closer to the ISO 7185 standard without compromising its Delphi processing in any way.

Is it possible to write in a Pascal subset that will be acceptable to both ISO 7185 Pascal and Delphi?

Sure. You can use the ISO 7185 "level 0" Pascal with the following omissions:

1. Do not use procedure or function parameters. These have different syntax in ISO 7185 and Delphi.

2. Do not use intraprocedural gotos (gotos that leave the current procedure or function). If you need a deep nested bailout to a higher level procedure, try setting an error variable and checking that after each procedure/function call that might have an error, then skipping either out of the routine, or to the goto point.

3. Do not use file buffer handling (such as f^ accesses, where f is a file), nor the built in routines "get" and "put". Basically, this just means you cannot use the lookahead buffering that ISO 7185 Pascal provides.

4. Do not size your variant records with "new". Delphi knows about variant records, but not how to size them (at least not the standard way). This will have no functional effect on your program, it will just take more runtime space.

5. Always use the keyword "packed" on a string that is intended to be printed with "writeln". Delphi does not require this, but ISO 7185 does.

6. Always include the files "input" and/or "output" in the program header if they are used in the program (and remember that write/read with no file parameter is a defacto reference). Delphi simply ignores these header parameters, so they don't hurt.

7. Always use format specifications to set the width that will be output for integers. This will remove differences from varying default fields.

8. Don't use external files other than input and output, since most Delphi does nothing with header files).

9. Borland Delphi has the requirement that an

{$APPTYPE CONSOLE}

must exist at the top after the program header. If your non-Delphi compiler ignores this as a comment, then you can add it to also be compatible with Delphi. If your ISO 7185 compiler also treats "$" in a comment as an option, you are going to have to be prepared to remove it as need be.

Finally, note that you MUST also comply with the ISO 7185 standard requirements for this to work. For example, ISO 7185 forbids gotos into program structures like "for" loops, etc, whereas delphi does not. There are many other such restrictions of ISO 7185 that are relaxed in Delphi, not to mention the many Delphi extensions that you need to refrain from using (of course, all Pascal compilers have extensions, so that would apply to them as well). Also remember: Pascal originally had no "string" type. This might seem strange, but C (for example) does not have one either. Instead, you use an array of characters (which is not the same thing!). See other sections of this FAQ.

The old bit of cross compiler checking that applies here is to run a check compile on all of the different compilers you plan to be compatible with frequently. This will tell you about problems with different compilers before they get out of hand.

For this author's point of view, I lived with mutiple Pascal compilers for years, and made it work by isolating system specific code to modules that implemented that on a particular platform. For example, I had a set of routines in a module I called "basicio.pas" that contained things like opentext(f, filename), closetext(f) and similar functions. Then, this module is simply recoded or swapped out to move to a different compiler.

Antrian Melingkar

Antrian Melingkar
uses wincrt;
type lingkar=array[1..10] of char;
type ling=record
nilai:lingkar;
dep:integer;
bel:integer;
isi:integer;
end;
var n:integer;
antrian:ling;
{---------------------------------------------------------------------}
procedure push(var antrian:ling;x:char);
7
begin
if antrian.isi=n then write('antrian penuh')
else
begin
if antrian.bel=n then antrian.bel:=1
else antrian.bel:=antrian.bel+1;
antrian.nilai[antrian.bel]:=x;
antrian.isi:=antrian.isi+1;
end;
end;
{---------------------------------------------------------------------}
procedure pop(var antrian:ling;var x:char);
begin
if antrian.isi=0 then write('antrian kosong')
else
begin
antrian.dep:=antrian.dep+1;
if antrian.dep=n+1 then antrian.dep:=1;
x:=antrian.nilai[antrian.dep];
antrian.nilai[antrian.dep]:=' ';
antrian.isi:=antrian.isi-1;
end;
end;
{---------------------------------------------------------------------}
var i,ingin:integer;
x:char;
begin
n:=5;
i:=0;
repeat
i:=i+1;
write('antrian ke - ',i,' = ');readln(x);
push(antrian,x);
until i=n;
for i:=1 to antrian.bel do write(antrian.nilai[i],' ');
readln;
repeat
write('Anda ingin 0. Udah, 1. Push, 2. pop');readln(ingin);
if ingin<>0 then
case ingin of
1: begin
write('nilai yang akan masuk : ');readln(x);
push(antrian,x);
for i:=1 to n do
write(antrian.nilai[i],' ');
writeln;
end;
2: begin
x:=' ';
pop(antrian,x);
writeln('Data keluar = ',x);
for i:=1 to n do
write(antrian.nilai[i],' ');
writeln;
end;
end
until ingin=0;
end.

Program Tumpukan

Program Tumpukan;
uses wincrt;
const MaxElemen=5;
type Tumpukan =record
isi:array[1..MaxElemen] of integer;
atas: 0..MaxElemen
end;
type isi=array[0..maxelemen] of integer;
const isilama1:isi=(3,7,2,6,4,8);
isibaru1:isi=(4,8,3,6,5,1);
var
Nilailama,Nilaibaru:isi;
T:tumpukan;
{---------------------------------------------------------------------}
Procedure Ganti_NilaiStack(T:tumpukan;Nilailama,Nilaibaru:isi);
var
penuh,habis: boolean;
x,i:integer;
{---------------------------------------------------------------------}
procedure push( var T:tumpukan; var penuh:boolean;x:integer);
begin
if T.atas = maxElemen then penuh:=true
else
begin
penuh :=false;
T.isi[T.atas]:=x;
T.atas:=T.atas+1;
end;
end;
{---------------------------------------------------------------------}
procedure pop(var T:tumpukan;var habis:boolean; var x:integer);
begin
if T.atas =0 then habis:=true
else
begin
habis:=false;
T.atas:=T.atas-1;
x:=T.isi[T.atas];
end;
end;
{---------------------------------------------------------------------}
begin
clrscr;
write('Nilai Lama Sebelum Masuk Tumpukan : ');
for i:=0 to maxelemen do
write(isilama1[i]);
writeln;
write('Nilai Baru Sebelum Masuk Tumpukan : ');
for i:=0 to maxelemen do
write(isibaru1[i]);
writeln;
penuh:=false;
while penuh=false do
begin
push(T,penuh,Nilailama[T.atas]);
end;
write('Isi Tumpukan Lama : ');
while T.atas<>0 do
begin
pop(T,habis,x);
write(x);
end;
writeln;penuh:=false;
while penuh=false do
begin
push(T,penuh,Nilaibaru[T.atas]);
end;
write('Isi Tumpukan Baru : ');
while T.atas<>0 do
begin
pop(T,habis,x);
write(x);
end;
end;
{---------------------------------------------------------------------}
begin
Nilailama:=isilama1;Nilaibaru:=isibaru1;
Ganti_NilaiStack(T,Nilailama,Nilaibaru);
readkey;
end.

Is it possible to have a module (unit) under Delphi that converts it to ISO 7185 use?

It is not possible for several reasons. First, there are several differences between the languages that are purely syntactic in nature, such as the way comments work. Second, there is no way to write, for example, file handling functions that accept all types of files. Third, there are features such as interprocedure gotos that only the compiler can implement.

I have seen many claims in the past that it is "easy to bridge the differences between ISO Pascal and the Delphi language", but it is usually apparent that those making the claim haven't read the ISO 7185 standard in any detail. It simply isn't that easy.

Program Ganjil Genap

Program ganjil_genap;
uses wincrt;
var
bil, i,g1,g2,j1,j2,n: integer;
rt1,rt2:real;
begin
write('Masukkan Banyaknya Data ' );readln(n);
for i := 1 to n do
begin
write('Bilangan ke:',i ,' ');readln(bil);
if bil mod 2 = 0 then
j1:=j1 +1;
g1:=g1+bil;
if bil mod 2 =1 then
j2:=j2+1;
g2:=g2+bil;
end;
rt1:=g1/j1;
rt2:=g2/j2;
writeln('Jumlah bil. Ganjil=' ,j2);
writeln('Jumlah bil. Genap=' ,j1);
writeln('Rerata Ganjil=' ,rt2:4:2);
writeln('Rerata Genap=' ,rt1:4:2);
end.

Program Baca berpasangan

Program Baca_berpasangan;
Uses WinCrt;
Var
X,Y,Rx,Ry,Jx,Jy : real;
Nx,Ny,i : integer;
Begin
ClrScr;
Write('Masukkan Banyaknya X :');Readln(Nx);
Write('Masukkan Banyaknya Y :');Readln(Ny);
If Nx = Ny then
For i:=1 to Nx Do
begin
Write('Data X ke-',i,' = ');Readln(X);
Write('Data Y ke-',i,' = ');Readln(Y);
Jx:=Jx+X;
Jy:=Jy+Y;
end
else if Nx > Ny then
begin
For i:=1 to Ny Do
begin
Write('Data X ke-',i,' = ');Readln(X);
Write('Data Y ke-',i,' = ');Readln(Y);
Jx:=Jx+X;
Jy:=Jy+Y;
end;
i:=Ny+1;
Repeat
Write('Data X ke-',i,' = ');Readln(X);
Jx:=Jx+X;
i:=i+1;
until i>Nx;
end
else if Nx < Ny then
begin
For i:=1 to Nx Do
begin
Write('Data X ke-',i,' = ');Readln(X);
Write('Data Y ke-',i,' = ');Readln(Y);
Jx:=Jx+X;
Jy:=Jy+Y;
end;
i:=Nx+1;
Repeat
Write('Data Y ke-',i,' = ');Readln(Y);
Jy:=Jy+Y;
i:=i+1;
until i>Ny;
end;
Rx:=Jx/Nx;
Ry:=Jy/Ny;
writeln('Rata-rata dari data X = ',Rx:6:2);
writeln('Rata-rata dari data Y = ',Ry:6:2);
end.

Differences between the languages Borland Delphi

Because Borland Delphi is a widely used version of Pascal, it is useful to compare the two languages. Note that here are presented only the differences between Borland Delphi and the basic ISO 7185 standard. Undiscussed are any extensions provided by Borland Delphi. In other words, this section answers the question "why doesn't my standard Pascal program run under Borland Delphi?", and perhaps "what can I write in Borland Delphi that will also be compatible with the ISO 7185 standard?".

1. Procedures and functions may not appear as parameters (it is true that it can be done, but a non-standard syntax must be used).

2. Goto statements cannot reference targets outside procedure/function bodies (so called "intraprocedural gotos").

3. No file buffer variable handling. Standard Pascal has file "buffer variables", and "get" and "put" procedures to operate on them. This functionality is not present in Borland Delphi.

4. No "sized" dynamic variable allocation. Given a variant record, the size of a particular variant cannot be specified as per the standard. I.e., the following statement is invalid:

new(p, t)

Where t is a variant record tag type.

5. The functions "pack" and "unpack" are not implemented.

6. { and (*, } and *) are not synonyms of each other as required by the standard. Ie.:

{ comment *)

is not valid in Borland Delphi (Delphi uses the scheme of allowing the different comment types to indicate nested comments).

7. It is not possible to construct a standard program without compiler directives. At minimum:

{$APPTYPE CONSOLE}

is required.

8. Does not replace eoln with space as the standard requires. When reading through the end of a line, the eoln character is supposed to be replaced with a space in ISO 7185. Instead, reading through eoln in Borland Delphi gives the character code for carriage return (13), followed by line feed (10).

9. Numbers and booleans are not printed out in their "default" field widths, but are printed in the minimum amount of space. For example:

write('>', 5, '<');

Outputs:

>5<

in Delphi, but:

> 5<

(spaces depend on compiler integer width) in ISO 7185.

For booleans:

write('>', true, '<');

outputs:

>true<

in Delphi, but:

> true<

In ISO 7185.

Comparision of Pascal and Borland Delphi

Pascal is a programming language, developed in 1970 by Niklaus Wirth.

An alternative dialect was created by Borland Corporation. Their language went through several versions and names, such as Turbo Pascal, Borland Pascal, and finally Delphi Pascal.

This page briefly goes over the differences between those dialects of the language.

The title of this page "Comparison between Pascal and Delphi" was chosen because Borland uses the name "Delphi" exclusively for their version of the language. It is correct to refer to "Pascal" in general as Niklaus Wirth's original language (and derivatives) and Borland's dialect as "Delphi". When referring to Borland's previous dialects, the terms "Turbo Pascal", and "Borland Pascal" apply.

The Term ISO 7185 or ISO 7185 Pascal is used here as synonymous with Niklaus Wirth's programming language Pascal. The ISO 7185 standard is the standardized version of Niklaus Wirth's language, as he has stated several times.