php将文本文件转换csv输出的方法

<?php
/** 
* Class to convert fixed width files into CSV format 
* Allows to set fields, separator, and end-of-line character 
* 
* @author Kevin Waterson 
* @url http://phpro.org 
* @version $Id$ 
* 
*/ 
class fixed2CSV extends SplFileObject 
{ 
/** 
* 
* Constructor, duh, calls the parent constructor 
* 
* @access       public 
* @param    string  The full path to the file to be converted 
* 
*/ 
public function __construct ( $filename ) 
{ 
parent :: __construct ( $filename ); 
}
 
/* 
* Settor, is called when trying to assign a value to non-existing property 
* 
* @access    public 
* @param    string    $name    The name of the property to set 
* @param    mixed    $value    The value of the property 
* @throw    Excption if property is not able to be set 
* 
*/ 
public function __set ( $name , $value ) 
{ 
switch( $name ) 
{ 
case 'eol' : 
case 'fields' : 
case 'separator' : 
$this -> $name = $value ; 
break;
 
default: 
throw new Exception ( "Unable to set $name " ); 
} 
}
 
/** 
* 
* Gettor This is called when trying to access a non-existing property 
* 
* @access    public 
* @param    string    $name    The name of the property 
* @throw    Exception if proplerty cannot be set 
* @return    string 
* 
*/ 
public function __get ( $name ) 
{ 
switch( $name ) 
{ 
case 'eol' : 
return " " ;
 
case 'fields' : 
return array();
 
case 'separator' : 
return ',' ;
 
default: 
throw new Exception ( " $name cannot be set" ); 
} 
}
 
/** 
* 
* Over ride the parent current method and convert the lines 
* 
* @access    public 
* @return    string    The line as a CSV representation of the fixed width line, false otherwise 
* 
*/ 
public function current () 
{ 
if( parent :: current () ) 
{ 
$csv = '' ; 
$fields = new cachingIterator ( new ArrayIterator ( $this -> fields ) ); 
foreach( $fields as $f ) 
{ 
$csv .= trim ( substr ( parent :: current (), $fields -> key (), $fields -> current ()  ) ); 
$csv .= $fields -> hasNext () ? $this -> separator : $this -> eol ; 
} 
return $csv ; 
} 
return false ; 
} 
} // end of class
?>

<?php
try 
{ 
/*** the fixed width file to convert ***/ 
$file = new fixed2CSV ( 'my_file.txt' );
 
/*** The start position=>width of each field ***/ 
$file -> fields = array( 0 => 10 , 10 => 15 , 25 => 20 , 45 => 25 );
 
/*** output the converted lines ***/ 
foreach( $file as $line ) 
{ 
echo $line ; 
}
 
/*** a new instance ***/ 
$new = new fixed2CSV ( 'my_file.txt' );
 
/*** get only first and third fields ***/ 
$new -> fields = array( 0 => 10 , 25 => 20 );
/*** output only the first and third fields ***/ 
foreach( $new as $line ) 
{ 
echo $line ; 
}
 
} 
catch( Exception $e ) 
{ 
echo $e -> getMessage (); 
}
?>