Re: [fpc-pascal] WORD (2 bytes) to String conversion
- Original Message - From: Graeme Geldenhuys graemeg.li...@gmail.com To: FPC-Pascal users discussions fpc-pascal@lists.freepascal.org Sent: Friday, October 23, 2009 11:10 PM Subject: [fpc-pascal] WORD (2 bytes) to String conversion Hi, I'm reading in a WORD (2 bytes) from a binary file. I can display the Hex format of that value without a problem, but I would also like to display the String value of that WORD variable. It's the first 2 bytes of a file, which contains the magic number of the file. I would like my program to output the following: - Header Section header.ID(5348h = HS) ... - Hi Graeme, What about something like this (variant records, similar to C unions)? (untested, ie. from memory, but shoud work) TMyHeader = Packed Record Case Integer Of 0 : (ID : Word); 1 : (IDStr : String[2]); End; You should then be able to file read/write it identically, and also do this: Var Header : TMyHeader; Begin WriteLn(Header.ID) ;// as a word WriteLn(Header.IDStr); // as a 2 byte string End; cheers, Paul ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] WORD (2 bytes) to String conversion
On Oct 25, 2009, at 3:09 PM, Paul Nicholls wrote: - Original Message - From: Graeme Geldenhuys graemeg.li...@gmail.com To: FPC-Pascal users discussions fpc-pascal@lists.freepascal.org Sent: Friday, October 23, 2009 11:10 PM Subject: [fpc-pascal] WORD (2 bytes) to String conversion Hi, I'm reading in a WORD (2 bytes) from a binary file. I can display the Hex format of that value without a problem, but I would also like to display the String value of that WORD variable. It's the first 2 bytes of a file, which contains the magic number of the file. I would like my program to output the following: - Header Section header.ID(5348h = HS) ... - Hi Graeme, What about something like this (variant records, similar to C unions)? (untested, ie. from memory, but shoud work) TMyHeader = Packed Record Case Integer Of 0 : (ID : Word); 1 : (IDStr : String[2]); End; Doesn't String[2] imply a length byte followed by 2 bytes for content = 3 bytes for a Pascal string? Even a C string of two characters content is 3 bytes. Just my $.03 Gary ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] WORD (2 bytes) to String conversion
Graeme Geldenhuys schreef: On 23/10/2009, Vincent Snijders vsnijd...@vodafonevast.nl wrote: You can consider declaring the ID in the header record type as array[1..2] of char. As Marco suggested... Char size might not always be the same. I did however change my header to array[0..1] of byte instead. But then you still cannot do: if header.id='HS' then // magic is correct. That is why I proposed a static array of char. Vincent ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] WORD (2 bytes) to String conversion
2009/10/24 Vincent Snijders vsnijd...@vodafonevast.nl: But then you still cannot do: if header.id='HS' then // magic is correct. That is why I proposed a static array of char. No, but I can do this... which is sufficient. var s: string begin s := hdr^.ID; if S = HS then ... -- Regards, - Graeme - ___ fpGUI - a cross-platform Free Pascal GUI toolkit http://opensoft.homeip.net/fpgui/ ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] WORD (2 bytes) to String conversion
Graeme Geldenhuys schreef: 2009/10/24 Vincent Snijders vsnijd...@vodafonevast.nl: But then you still cannot do: if header.id='HS' then // magic is correct. That is why I proposed a static array of char. No, but I can do this... which is sufficient. var s: string begin s := hdr^.ID; if S = HS then ... Not with fpc, I guess, otherwise I learned two new features: * string constants that are surrounded with double quotes * assignment to static array of byte to a string without conversion What type is ID? Vincent ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] WORD (2 bytes) to String conversion
As Marco suggested... Char size might not always be the same. Why that? I hope noone changes the meaning of such long-time types some day. If a new type is needed, then it should get a new name too. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
[fpc-pascal] WORD (2 bytes) to String conversion
Hi, I'm reading in a WORD (2 bytes) from a binary file. I can display the Hex format of that value without a problem, but I would also like to display the String value of that WORD variable. It's the first 2 bytes of a file, which contains the magic number of the file. I would like my program to output the following: - Header Section header.ID(5348h = HS) ... - -- Regards, - Graeme - ___ fpGUI - a cross-platform Free Pascal GUI toolkit http://opensoft.homeip.net/fpgui/ ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] WORD (2 bytes) to String conversion
On Fri, Oct 23, 2009 at 14:10, Graeme Geldenhuys graemeg.li...@gmail.com wrote: Hi, I'm reading in a WORD (2 bytes) from a binary file. I can display the Hex format of that value without a problem, but I would also like to display the String value of that WORD variable. It's the first 2 bytes of a file, which contains the magic number of the file. I would like my program to output the following: - Header Section header.ID (5348h = HS) ... - w: WORD ... YourString := Chr(Lo(w)) + Chr(Hi(w)) or YourString := Chr(Hi(w)) + Chr(Lo(w)) (depending on endianness) -- Regards, - Graeme - ___ fpGUI - a cross-platform Free Pascal GUI toolkit http://opensoft.homeip.net/fpgui/ ___ fpc-pascal maillist - fpc-pas...@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal -- Aleksa Todorovic - Lead Programmer Eipix Entertainment http://www.eipix.com/ ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] WORD (2 bytes) to String conversion
2009/10/23 Aleksa Todorovic alexi...@gmail.com: w: WORD ... YourString := Chr(Lo(w)) + Chr(Hi(w)) or YourString := Chr(Hi(w)) + Chr(Lo(w)) Ah, thanks. I was close, I used High() and Low() instead. :-( Dope! -- Regards, - Graeme - ___ fpGUI - a cross-platform Free Pascal GUI toolkit http://opensoft.homeip.net/fpgui/ ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] WORD (2 bytes) to String conversion
Graeme Geldenhuys wrote: Hi, I'm reading in a WORD (2 bytes) from a binary file. I can display the Hex format of that value without a problem, but I would also like to display the String value of that WORD variable. It's the first 2 bytes of a file, which contains the magic number of the file. Personally, I'd do something like this, as it is more explicit (you won't be left wondering what magic occurred later: function WordToString(w: word): String; begin Result := Char(hi(w)) + Char(lo(w)); end; That's dangerous, though, if your magic number's two bytes aren't printable ASCII. I believe there is an RTL function like IsPrintableASCII or something like that that you could check each character with. Jeff. -- I haven't smoked for 3 years, 2 months and 6 days, saving $5,235.38 and not smoking 34,902.58 cigarettes. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] WORD (2 bytes) to String conversion
On 23/10/2009, Jeff Wormsley dawor...@comcast.net wrote: That's dangerous, though, if your magic number's two bytes aren't printable That should never be a problem for my tool though. The tool I am writing is specific to the INF help format. The tool dumps the file structure to a text file. (I need this for debugging purposes) When my app processes a file, it reads the first 155 bytes (header information), then does a numerical check of the magic number in the header. If it's an unknown value, it stops right there. If it's a known value, it continues at which point it starts outputing the text to file. -- Regards, - Graeme - ___ fpGUI - a cross-platform Free Pascal GUI toolkit http://opensoft.homeip.net/fpgui/ ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] WORD (2 bytes) to String conversion
Graeme Geldenhuys wrote: On 23/10/2009, Jeff Wormsley dawor...@comcast.net wrote: That's dangerous, though, if your magic number's two bytes aren't printable That should never be a problem for my tool though. The tool I am writing is specific to the INF help format. The tool dumps the file structure to a text file. (I need this for debugging purposes) Oh, I was fairly certain of that. Its just these little routines tend to end up in libraries of handy code. I tend to be overly cautious with some of these because of that. Jeff. -- I haven't smoked for 3 years, 2 months and 6 days, saving $5,235.76 and not smoking 34,905.07 cigarettes. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] WORD (2 bytes) to String conversion
On 23/10/2009, Jeff Wormsley dawor...@comcast.net wrote: Oh, I was fairly certain of that. Its just these little routines tend to end up in libraries of handy code. I tend to be overly cautious with some of these because of that. Point taken. :-) This code is purposely rewritten and totally standalone so I can track down a bug in my actual project, the INF DocView project. -- Regards, - Graeme - ___ fpGUI - a cross-platform Free Pascal GUI toolkit http://opensoft.homeip.net/fpgui/ ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] WORD (2 bytes) to String conversion
I would like my program to output the following: - Header Section header.ID(5348h = HS) ... - Wouldn't it be more direct to use Blockwrite(file,header.ID,sizeof(header.ID)); That would make it robust against changes of ID size and would avoid the many type castings. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] WORD (2 bytes) to String conversion
On 23/10/2009, Jürgen Hestermann juergen.hesterm...@gmx.de wrote: Wouldn't it be more direct to use Blockwrite(file,header.ID,sizeof(header.ID)); I read the complete header structure in one go (155 bytes). I simply want to output to a text file, a human readable structure of the complete INF file. The INF file format is quite complex and one can easily get confuse between various bits of information all in various locations inside the file. The tool I am writing is imply so I can see in a more visual way the various bits of information, without the need for a hex editor etc... So the solution described earlier will suffice for my needs. -- Regards, - Graeme - ___ fpGUI - a cross-platform Free Pascal GUI toolkit http://opensoft.homeip.net/fpgui/ ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] WORD (2 bytes) to String conversion
Graeme Geldenhuys schreef: On 23/10/2009, Jürgen Hestermann juergen.hesterm...@gmx.de wrote: Wouldn't it be more direct to use Blockwrite(file,header.ID,sizeof(header.ID)); I read the complete header structure in one go (155 bytes). I simply want to output to a text file, a human readable structure of the complete INF file. The INF file format is quite complex and one can easily get confuse between various bits of information all in various locations inside the file. The tool I am writing is imply so I can see in a more visual way the various bits of information, without the need for a hex editor etc... So the solution described earlier will suffice for my needs. You can consider declaring the ID in the header record type as array[1..2] of char. Vincent ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] WORD (2 bytes) to String conversion
On 23/10/2009, Vincent Snijders vsnijd...@vodafonevast.nl wrote: You can consider declaring the ID in the header record type as array[1..2] of char. As Marco suggested... Char size might not always be the same. I did however change my header to array[0..1] of byte instead. -- Regards, - Graeme - ___ fpGUI - a cross-platform Free Pascal GUI toolkit http://opensoft.homeip.net/fpgui/ ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
