php man page for fwrite

FWRITE(3)								 1								 FWRITE(3)

fwrite - Binary-safe file write

SYNOPSIS
       int fwrite (resource  $handle, string  $string, [int  $length])

DESCRIPTION
       fwrite(3) writes the contents of $string to the file stream pointed to by $handle.

PARAMETERS
	      o $handle
		-A file system pointer resource that is typically created using fopen(3).

	      o $string
		- The string that is to be written.

	      o $length
		-  If  the  $length  argument  is given, writing will stop after $length bytes have been written or the end of $string is reached,
		whichever comes first.	Note that if the $length argument is given, then the magic_quotes_runtime  configuration  option  will	be
		ignored and no slashes will be stripped from $string.

RETURN VALUES
       fwrite(3) returns the number of bytes written, or FALSE on error.

NOTES
       Note

	       Writing to a network stream may end before the whole string is written. Return value of fwrite(3) may be checked:

	      <?php
	      function fwrite_stream($fp, $string) {
		  for ($written = 0; $written < strlen($string); $written += $fwrite) {
		      $fwrite = fwrite($fp, substr($string, $written));
		      if ($fwrite === false) {
			  return $written;
		      }
		  }
		  return $written;
	      }
	      ?>

       Note

	       On  systems  which differentiate between binary and text files (i.e. Windows) the file must be opened with 'b' included in fopen(3)
	      mode parameter.

       Note

	       If $handle was fopen(3)ed in append mode, fwrite(3)s are atomic (unless the size of $string exceeds the filesystem's block size, on
	      some  platforms,	and as long as the file is on a local filesystem). That is, there is no need to flock(3) a resource before calling
	      fwrite(3); all of the data will be written without interruption.

       Note

	       If writing twice to the file pointer, then the data will be appended to the end of the file content:

	      <?php
	      $fp = fopen('data.txt', 'w');
	      fwrite($fp, '1');
	      fwrite($fp, '23');
	      fclose($fp);

	      // the content of 'data.txt' is now 123 and not 23!
	      ?>

EXAMPLES
       Example #1

	      A simple fwrite(3) example

	      <?php
	      $filename = 'test.txt';
	      $somecontent = "Add this to the file
";

	      // Let's make sure the file exists and is writable first.
	      if (is_writable($filename)) {

		  // In our example we're opening $filename in append mode.
		  // The file pointer is at the bottom of the file hence
		  // that's where $somecontent will go when we fwrite() it.
		  if (!$handle = fopen($filename, 'a')) {
		       echo "Cannot open file ($filename)";
		       exit;
		  }

		  // Write $somecontent to our opened file.
		  if (fwrite($handle, $somecontent) === FALSE) {
		      echo "Cannot write to file ($filename)";
		      exit;
		  }

		  echo "Success, wrote ($somecontent) to file ($filename)";

		  fclose($handle);

	      } else {
		  echo "The file $filename is not writable";
	      }
	      ?>

SEE ALSO
       fread(3), fopen(3), fsockopen(3), popen(3), file_get_contents(3).

PHP Documentation Group 														 FWRITE(3)