quirks in writing text to file
lazarus / 12-Debugger

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daringly · 2023-10-07 22:16

These two codes give very different output. There is a weird character
in teststring that disables output to the textfile, and it looks like
'' or ", not sure which.

assign(fila);
rewrite(fila);
writeln(fila,teststring);
close(fila);

vs
writeln(teststring);

These two codes give very different output. There is a weird character
in teststring that disables output to the textfile. The second time
you write this code, writing to the file works normally.

If I look at the string's first character in debug, I get
pchar: 77 'M' String: 34 '\"'

How can I identify and remove this escape code from the string so that
the visual and file output are similar?

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Martin_fr · 2023-10-07 22:58

Quote from: daringly on October 08, 2023, 12:16:59 am
If I look at the string's first character in debug, I get
pchar: 77 'M' String: 34 '\"'

About the debuggers output.

Depending on various things, the fpc compiler does not give the
debugger enough info if your variable is a pchar, or a string.
However if you watch something like "MyText[1]" in a string "[1]"
means the first char. A pchar however starts at index 0, sot "[1]" is
the 2nd char. => the debugger shows both.


For the rest I am not sure, 77 would be M
32 would be "  (not sure why it is shown with a \ before)

I don't know why they affect your file. Have you looked at it in a hex
editor?

Also why do you only look at the FIRST char in the debugger? Maybe the
issues is a later char?

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daringly · 2023-10-07 23:10

Thanks.

I looked at 0 and 1. Everything after the first 2 characters is
"normal" compared to other strings that work normally.
With string[0], pchar is 34.

When I removed that first character (using rightstr, skipping first
character) the text file worked correctly.

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TRon · 2023-10-08 06:49

Quote from: daringly on October 08, 2023, 01:10:30 amWhen I removed
that first character (using rightstr, skipping first character) the
text file worked correctly.
In which case that can only lead to one conclusion and that is that
the 'wrong' character was already present in your teststring otherwise
it would not have ended up in your file. It could be the 'wrong'
character isn't printable in the terminal (e.g. presentable by a
visible ascii/utf character).

Anything else without compilable code that is capable of reproducing
the error is just pure speculation.

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i program
test; {$mode objfpc}{$H+} uses  sysutils; procedure
WriteTestString(teststring: string);var  fd: textfile;begin  // write
to terminal  WriteLn(teststring);   // write to file  AssignFile(fd,
'some_test_file.txt');   {$push}  {$I+}  try    Rewrite(fd);   
writeln(fd, teststring);    CloseFile(fd);  except    on E:
EInOutError      do writeln('ERROR: error occurred during file
operation: ', E.ClassName, ' / ', E.Message);  end;  {$pop}end; begin 
WriteTestString('"This is a test string."');end.