Tag: files

Delphi: Remove Directory Recursively

Frédéric Hannes

If you ended up looking for this, then you probably came to the conclusion that Windows.RemoveDirectory() can not remove a directory that has files/directories in it.

About.com proposes the following solution: http://delphi.about.com/cs/adptips1999/a/bltip1199_2.htm

I can assure you that this solution is valid and works. However, the code as it is proposed there will move the deleted folder into the recycle bin which is something you will want to avoid more often than not. The following code I modified to remove that effect:

Another way of doing this is recursing through all directories and removing all files before you remove the directories as seen here, but I imagine that might be slower as in the method above, the OS takes care of that internally:

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Delphi: FileSystem Searching

Frédéric Hannes

The windows api comes with several functions to search through files in a computer’s filesystem such as FindFirstFile, FindNextFile, … The RTL library in Delphi encapsulates these functions in 3 easy to use functions. These are FindFirst, FindNext and FindClose. Unlike what you may be used to from the win32 api, these functions return 0 not if something went wrong, but if they were successful. You have to pass the function a mask for the files, this consists out of a filemask to search in the current directory or a filemask including a folderpath. An example would be “c:\*”, this would return all files or folders in c:\ depending on what flags you pass to the FindFirst function. Note that the functions are not recursive, so they will only return the content of a folder and not it’s subfolders. The second parameter of the FindFirst function specifies flags that tell the functions what it is searching for. A few flags are faNormal, faHidden, faSysFile, faDirectory, … These can also be combined to select several types of files/directories. The following example shows you how to loop through all files and directories in the c:\ folder:

program FindTest;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var
  sRec: TSearchRec;
begin
  if FindFirst('c:*', faNormal or faDirectory, sRec) = 0 then
  begin
    repeat
      WriteLn(sRec.Name + ' - ' + IntToStr(sRec.Size));
    until FindNext(sRec) <> 0;
    FindClose(sRec);
  end;
  ReadLn; // Prevent window from closing
end.

If you would for example change your mask to “c:\*.txt”, it would only return the txt files.

Some of you will also want to be able to recurse this, this can easily be achieved by setting it up in a recursive algoritm:

program FindTest;

{$APPTYPE CONSOLE}

uses
  SysUtils;

procedure RecurseFileSystem(const Folder, Mask: string);
var
  sRec: TSearchRec;
  t: string;
begin
  t := IncludeTrailingPathDelimiter(Folder);
  if FindFirst(t + Mask, faNormal or faDirectory, sRec) = 0 then
  begin
    repeat
      if ((sRec.Attr and faDirectory) <> 0) and (sRec.Name <> '.') and
        (sRec.Name <> '..') then
        RecurseFileSystem(t + sRec.Name, Mask)
      else
        WriteLn(t + sRec.Name + ' - ' + IntToStr(sRec.Size));
    until FindNext(sRec) <> 0;
    FindClose(sRec);
  end;
end;

begin
  RecurseFileSystem('c:', '*');
  ReadLn; // Prevent window from closing
end.

This example will loop through the entire filesystem on the c drive and show you all of the regular files including their path and size.

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Java: Reading and writing text files

Frédéric Hannes

A lot of people starting off with Java will often want to read or write text files. Here’s some code to do just that:

public static String readFile(String fileName) throws IOException {
	FileInputStream fis = new FileInputStream(fileName);
	BufferedInputStream bis = new BufferedInputStream(fis, 1024);
	byte[] buffer = new byte[1024];
	String result = "";
	int len;
	while ((len = bis.read(buffer)) != -1) {
		byte[] tmp = new byte[len];
		System.arraycopy(buffer, 0, tmp, 0, len);
		result += new String(tmp);
	}
	bis.close();
	return result;
}

public static void writeFile(String fileName, String content)
		throws IOException {
	FileOutputStream fos = new FileOutputStream(fileName);
	BufferedOutputStream bos = new BufferedOutputStream(fos, 1024);
	bos.write(content.getBytes());
	bos.close();
}

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