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File: example-with-variable-header.php

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  Classes of Christian Vigh  >  Random Access File  >  example-with-variable-header.php  >  Download  
File: example-with-variable-header.php
Role: Example script
Content type: text/plain
Description: Example script
Class: Random Access File
Store data fixed record length data in files
Author: By
Last change:
Date: 6 years ago
Size: 2,008 bytes
 

Contents

Class file image Download
<?php
   
/***
        This example opens a file (random-with-variable-header.dat) having the following contents :

            "!This is a variable-length headerRecord01Record02Record03"

        In this case, the header is a variable-size header (ie, its length may depend on your file structure).
        It has been decided in this example that the size of the header would be given by the first byte, an
        exclamation point, which is ascii value 33.
        Hence the length of the header (including the first byte) is 33 and contains :

            "!This is a variable-length header"

        A callback function is specified in place of the $header_size parameter of the constructor, to allow the
        class to retrieve the correct length of the header.

        The file contains 3 records, "Record01" through "Record03", of length 8.

        The script then displays :
        - The header contents
        - The number of records
        - Each individual record

     ***/
   
require ( "RandomAccessFile.phpclass" ) ;

    if (
php_sapi_name ( ) != 'cli' )
        echo
"<pre>" ;

   
$random_file = "random-with-variable-header.dat" ;

   
// Open the random access file of record size 8, specifying a closure function instead of an integer header size.
    // The closure function will read the first byte, which contains the actuel length of the header. This function
    // is called whenever the Open() method of the RandomAccessFile class is called.
   
$rf = new RandomAccessFile
      
(
       
$random_file,
       
8,
        function (
$fd )
           {
           
$ch = fread ( $fd, 1 ) ; // Read the first byte of our sample file, which contains the header size.

           
return ( ord ( $ch ) ) ; // Return the size in bytes
           
}
        ) ;

   
// Open the file in read-only mode
   
$rf -> Open ( true ) ;

   
// Display data
   
echo "HEADER DATA : [{$rf -> Header}]\n" ;
    echo
"HEADER SIZE : {$rf -> HeaderSize}\n" ;
    echo
"RECORD COUNT : " . count ( $rf ) . "\n" ;
   
    for (
$i = 0 ; $i < count ( $rf ) ; $i ++ )
        echo
"RECORD #" . ( $i + 1 ) . " : [{$rf [$i]}]\n" ;

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