String truncates to the length of the first string in the array (compiler bug?)

[stoffman]

I'm using windows 10, Laz 2.2.4, FPC 3.2.2

In the first loop, it doesn't print 'abcde' but just 'abcd' , on the second loop it works correctly (see the attached image)

Code: Pascal  [Select][+][-]

1. procedure TForm1.Button1Click(Sender: TObject);
2. var
3.   s : string;
4. begin
5.   for s in ['1234','acbde'] do
6.     OutputDebugString(PChar(s));
7.  
8.   for s in ['acbde','1234'] do
9.     OutputDebugString(PChar(s));
10. end;

I suspect this is a bug in the compiler. Where do I report this?


Thanks

[TRon]

Trunk seem to have it fixed. I can verify the behaviour with the 3.2.2. compiler

[Thaddy]

It is not a bug, but the casts to PChar!
Pascal allows #0 within a string, a PChar uses #0 as a string terminator. It is simply a silly programmer error. A Pascal string  <> a Pchar.
It borders at sheer stupidity. or not reading manuals.

And for good measure, this has ALWAYS been the case. Nothing to do with any FreePascal version.

I have demonstrated that many times on this forum.

Code: Pascal  [Select][+][-]

1. program crashtestdummy;
2. const test:string = 'hello,'#0'world';
3. begin
4.   writeln(test);
5.   writeln(pchar(test));
6.   readln; // just for windows users
7. end.

Sigh...

[TRon]

It is not a bug, but the casts to PChar!

You seem to have had a different opinion on that same topic 6 years ago 

[VisualLab]

I did a test too. I am attaching the source code and a screenshot of the console window. Let everyone check it out for themselves.

Code: Pascal  [Select][+][-]

1. program Project1;
2.  
3. const
4.   SIndent = ' ->';
5.  
6. var
7.   LText: String;
8.   LArrayText1, LArrayText2: array [0..1] of String;
9.   i: Integer;
10.  
11. begin
12.   // using the array of strings given in the loop (for..in)
13.   WriteLn('Using the array of strings given in the loop (for..in):');
14.   WriteLn;
15.   WriteLn('As Pascal string (numbers, text):');
16.   for LText in ['1234', 'acbde'] do
17.     WriteLn(SIndent + LText);
18.   WriteLn;
19.   WriteLn('As Pascal string (text, numbers):');
20.   for LText in ['acbde', '1234'] do
21.     WriteLn(SIndent + LText);
22.   WriteLn;
23.   WriteLn('As PChar (numbers, text):');
24.   for LText in ['1234', 'acbde'] do
25.     WriteLn(SIndent + PChar(LText));
26.   WriteLn;
27.   WriteLn('As PChar (text, numbers):');
28.   for LText in ['acbde', '1234'] do
29.     WriteLn(SIndent + PChar(LText));
30.   // using the array of strings defined earlier (for..to..do)
31.   WriteLn;
32.   WriteLn('========');
33.   WriteLn;
34.   WriteLn('Using the array of strings defined earlier (for..to..do):');
35.   WriteLn;
36.   LArrayText1[0] := '1234';
37.   LArrayText1[1] := 'acbde';
38.   LArrayText2[0] := 'acbde';
39.   LArrayText2[1] := '1234';
40.   WriteLn('As Pascal string (numbers, text):');
41.   for i := 0 to 1 do
42.     WriteLn(SIndent + LArrayText1[i]);
43.   WriteLn;
44.   WriteLn('As Pascal string (text, numbers):');
45.   for i := 0 to 1 do
46.     WriteLn(SIndent + LArrayText2[i]);
47.   WriteLn;
48.   WriteLn('As PChar (numbers, text):');
49.   for i := 0 to 1 do
50.     WriteLn(SIndent + PChar(LArrayText1[i]));
51.   WriteLn;
52.   WriteLn('As PChar (text, numbers):');
53.   for i := 0 to 1 do
54.     WriteLn(SIndent + PChar(LArrayText2[i]));
55.   // prevent the console window from closing
56.   ReadLn;
57. end.

---
Edit: I used Lazarus 2.2.6.

[TRon]

For heavens sake. It is fixed with commit https://gitlab.com/freepascal.org/fpc/source/-/commit/815734c47a4afe7d07083757f9ed6df233762abb

[stoffman]

It is not a bug, but the casts to PChar!
Pascal allows #0 within a string, a PChar uses #0 as a string terminator. It is simply a silly programmer error. A Pascal string  <> a Pchar.
It borders at sheer stupidity. or not reading manuals.

And for good measure, this has ALWAYS been the case. Nothing to do with any FreePascal version.

I have demonstrated that many times on this forum.

Code: Pascal  [Select][+][-]

1. program crashtestdummy;
2. const test:string = 'hello,'#0'world';
3. begin
4.   writeln(test);
5.   writeln(pchar(test));
6.   readln; // just for windows users
7. end.

Sigh...

Did you see the example? did you read the example? did you understand the example?

Obviously you failed at one of these tasks before answering. Please try better next time. 

[jamie]

Oh, Thaddy, pay no mind to the shoot first and Oops, ask questions later guy!

Just noise in the background that gets attenuated with the Noise Blanker switch!

[PascalDragon]

For heavens sake. It is fixed with commit https://gitlab.com/freepascal.org/fpc/source/-/commit/815734c47a4afe7d07083757f9ed6df233762abb

And it's also been merged to 3.2.3, so it will be in 3.2.4.