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digitalmars.D.learn - Check whether a file is empty.

reply Vino <vino.bheeman hotmail.com> writes:
Hi All,

   Request your help on how to check whether a given file is 
empty, I tried the getSize from std.file but no luck as in 
windows 7 is the file is empty the size of the file is 0 bytes 
but in Windows 2003 if the file is empty the size of the file 
show as 2 bytes.


From,
Vino.B
Dec 08 2017
next sibling parent Kagamin <spam here.lot> writes:
Other functions that can be used for this are 
GetFileInformationByHandle, GetFileSizeEx, SetFilePointerEx or 
File.size in phobos.
Dec 08 2017
prev sibling parent reply FreeSlave <freeslave93 gmail.com> writes:
On Friday, 8 December 2017 at 09:40:18 UTC, Vino wrote:

 Hi All,

   Request your help on how to check whether a given file is 
 empty, I tried the getSize from std.file but no luck as in 
 windows 7 is the file is empty the size of the file is 0 bytes 
 but in Windows 2003 if the file is empty the size of the file 
 show as 2 bytes.


 From,
 Vino.B


Was it the same file on Windows 7 and Windows 2003?
Maybe the file on Windows 2003 had a byte order mark or carriage 
return + newline characters.
Dec 08 2017
parent reply vino <vino.bheeman hotmail.com> writes:
On Friday, 8 December 2017 at 12:25:19 UTC, FreeSlave wrote:

 On Friday, 8 December 2017 at 09:40:18 UTC, Vino wrote:

 Hi All,

   Request your help on how to check whether a given file is 
 empty, I tried the getSize from std.file but no luck as in 
 windows 7 is the file is empty the size of the file is 0 bytes 
 but in Windows 2003 if the file is empty the size of the file 
 show as 2 bytes.


 From,
 Vino.B


 Was it the same file on Windows 7 and Windows 2003?
 Maybe the file on Windows 2003 had a byte order mark or 
 carriage return + newline characters.


Hi,

  The code is same just copy pasted the code form Windows 7 into 
Windows 2003 and executed, in Windows 7 the log file is of size 0 
where as in windows 2003 the log file is of size 2 byte where the 
log file in both the server is empty.

From,
Vino.B
Dec 08 2017
next sibling parent codephantom <me noyb.com> writes:
On Friday, 8 December 2017 at 19:13:20 UTC, vino wrote:

 Hi,

  The code is same just copy pasted the code form Windows 7 into 
 Windows 2003 and executed, in Windows 7 the log file is of size 
 0 where as in windows 2003 the log file is of size 2 byte where 
 the log file in both the server is empty.

 From,
 Vino.B


It certainly sounds like some kind of encoding issue.

I guess you don't have much choice other than to read the 
contents of the file, and determine what it actually contains.

Assuming these log files of yours are 'ascii text' files, then if 
the file is less than say .. 5 bytes.. you could check if it 
*only* contained *non-printable* characters, in which case it's 
'likely' an empty file.

something very silly, like this, might do it ;-)

// -------

bool isFileLikelyEmpty(string filename)
{

     import std.exception, std.file, std.ascii, std.conv;

     File f = filename;

     enforce(f.size < 5,
         "This file is not likely to be empty." ~
         " No point in continuing."); // 5 seems reasonable cutoff 
;-)

     bool result = false;
     int charCount = 0;
     auto str = readText(filename);

     foreach(c; str)
     {
         // https://dlang.org/phobos/std_ascii.html#isPrintable
         if( !isPrintable(c) )
             charCount++;
     }

     if(charCount == str.length)
         result = true; // file is likely empty, as all characters 
are non-printable.

     return result;
}

// ---------
Dec 08 2017
prev sibling parent FreeSlave <freeslave93 gmail.com> writes:
On Friday, 8 December 2017 at 19:13:20 UTC, vino wrote:

 Hi,

  The code is same just copy pasted the code form Windows 7 into 
 Windows 2003 and executed, in Windows 7 the log file is of size 
 0 where as in windows 2003 the log file is of size 2 byte where 
 the log file in both the server is empty.

 From,
 Vino.B


What do you mean exactly by empty log file? If the file looks 
blank in notepad it does not mean it's empty. What are those 2 
bytes?
Which program does create this file? It may work differently 
depending on the system or different versions are installed.
Dec 09 2017