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 ();  
} 
?>