Truncate a file: Difference between revisions

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 </lang>
-==Icon and {{header|Unicon}}==
+=={{header|Icon}} and {{header|Unicon}}==
 Unicon provides the built-in function truncate which can be used to truncate a file.  The following line of code truncates ''filename'' to ''newsizeinbytes''.  The file is opened for both read and write in untranslated mode.
 <lang Unicon>truncate(f := open(filename, "bu"), newsizeinbytes) & close(f)</lang>
@@ Line 144: / Line 144: @@
 	}
 }</lang>
-=={{header|OCaml}}==
-The <code>Unix</code> module provided with the standard distribution provides a function <code>[http://caml.inria.fr/pub/docs/manual-ocaml/libref/Unix.html#VALtruncate truncate]</code>:
-<lang ocaml>val truncate : string -> int -> unit
-(** Truncates the named file to the given size. *)</lang>
-There is also a function <code>[http://caml.inria.fr/pub/docs/manual-ocaml/libref/Unix.html#VALftruncate ftruncate]</code> that does the equivalent operation but with a file descriptor instead of a file name:
-<lang ocaml>val ftruncate : file_descr -> int -> unit
-(** Truncates the file corresponding to the given descriptor to the given size. *)</lang>
 =={{header|Liberty BASIC}}==
@@ Line 194: / Line 182: @@
 </lang>
+=={{header|OCaml}}==
+The <code>Unix</code> module provided with the standard distribution provides a function <code>[http://caml.inria.fr/pub/docs/manual-ocaml/libref/Unix.html#VALtruncate truncate]</code>:
-=={{header|PureBasic}}==
-PureBasic has the internal function [http://www.purebasic.com/documentation/file/truncatefile.html TruncateFile] that cuts the file at the current file position and discards all data that follows.
+<lang ocaml>val truncate : string -> int -> unit
-<lang PureBasic>Procedure SetFileSize(File$, length.q)
+(** Truncates the named file to the given size. *)</lang>
-  Protected fh, pos, i
-  If FileSize(File$) < length
+There is also a function <code>[http://caml.inria.fr/pub/docs/manual-ocaml/libref/Unix.html#VALftruncate ftruncate]</code> that does the equivalent operation but with a file descriptor instead of a file name:
-    Debug "File to small, is a directory or does not exist."
-    ProcedureReturn #False
+<lang ocaml>val ftruncate : file_descr -> int -> unit
-  Else
+(** Truncates the file corresponding to the given descriptor to the given size. *)</lang>
-    fh = OpenFile(#PB_Any, File$)
-    FileSeek(fh, length)
+=={{header|Pascal}}==
-    TruncateFile(fh)
+<lang pascal>
-    CloseFile(fh)
+Program FileTruncate;
-  EndIf
-  ProcedureReturn #True
+uses
-EndProcedure</lang>
+  SysUtils;
+var
+  myfile:   file of byte;
+  filename: string;
+  position: integer;
+begin
+  write('File for truncation: ');
+  readln(filename);
+  if not FileExists(filename) then
+  begin
+    writeln('Error: File does not exist.');
+    exit;
+  end;
+  write('Truncate position: ');
+  readln(position);
+  Assign(myfile, filename);
+  Reset(myfile);
+  if FileSize(myfile) < position then
+  begin
+    writeln('Warning: The file "', filename, '" is too short. No need to truncate at position ', position);
+    Close(myfile);
+    exit;
+  end;
+  Seek(myfile, position);
+  Truncate(myfile);
+  Close(myfile);
+  writeln('File "', filename, '" truncated at position ', position, '.');
+end.
+</lang>
+Output:
+<pre>
+File for truncation: test
+Truncate position: 3
+File "test" truncated at position 3.
+</pre>
 =={{header|Perl}}==
@@ Line 227: / Line 256: @@
 <lang PicoLisp>(de truncate (File Len)
    (call "truncate" "-s" Len File) )</lang>
+=={{header|PureBasic}}==
+PureBasic has the internal function [http://www.purebasic.com/documentation/file/truncatefile.html TruncateFile] that cuts the file at the current file position and discards all data that follows.
+<lang PureBasic>Procedure SetFileSize(File$, length.q)
+  Protected fh, pos, i
+  If FileSize(File$) < length
+    Debug "File to small, is a directory or does not exist."
+    ProcedureReturn #False
+  Else
+    fh = OpenFile(#PB_Any, File$)
+    FileSeek(fh, length)
+    TruncateFile(fh)
+    CloseFile(fh)
+  EndIf
+  ProcedureReturn #True
+EndProcedure</lang>
 =={{header|Python}}==