PHP read file as an array of bytes

Question

I have a file written using JAVA program which has an array of integers written as binary I made an for loop over this array and write it using this method

public static void writeInt(OutputStream out, int v) throws IOException {
    out.write((v >>> 24) & 0xFF);
    out.write((v >>> 16) & 0xFF);
    out.write((v >>> 8) & 0xFF);
    out.write((v >>> 0) & 0xFF);
}

I'm ask about how to read this file in PHP.

@Orangepill I'm new in php and it is hard to dial with manual alone can you help me in a piece of code assume we start reading file with this code $filename = "myFile.sav"; $handle = fopen($filename, "rb"); $contents = fread($handle, filesize($filename)); — BlackRoot
– BlackRoot, Commented Jul 31, 2013 at 6:34

BlackRoot · Accepted Answer · 2013-07-31 07:19:45Z

16

I believe the code you are looking for is:

$byteArray = unpack("N*",file_get_contents($filename));

UPDATE: Working code supplied by OP

$filename = "myFile.sav"; 
$handle = fopen($filename, "rb"); 
$fsize = filesize($filename); 
$contents = fread($handle, $fsize); 
$byteArray = unpack("N*",$contents); 
print_r($byteArray); 
for($n = 0; $n < 16; $n++)
{ 
    echo $byteArray [$n].'<br/>'; 
}

edited Jul 31, 2013 at 7:19

BlackRoot

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answered Jul 31, 2013 at 6:39

Orangepill

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4 Comments

BlackRoot Over a year ago

Thanks Thanks Thanks Orangepill this is what i'm looking for. the code i'm use :

$filename = "myFile.sav"; $handle = fopen($filename, "rb"); $fsize = filesize($filename); $contents = fread($handle, $fsize); $byteArray = unpack("N*",$contents);  print_r($byteArray);  for($n = 1; $n <= 16; $n++){ 	echo $byteArray [$n].'<br/>'; }

FredFury Over a year ago

I could not get this to work. The example code fails at the unpack. Might be because of the file I'm attempting to read?

Codie Morgan Over a year ago

shouldn't it also be a good idead to call fclose on the file resource in the working example?

qrsngky Over a year ago

I found that this results in an array of 32-bit integers, so I'm not sure if the name $byteArray is appropriate. To get 8-bit integers, I had to use C* instead of N*

Joni · Accepted Answer · 2013-07-31 06:38:49Z

5

You should read the file as a string and then use unpack to parse it. In this case you have stored a 32-bit integer in big endian byte order, so use:

$out = unpack("N", $in);

The format codes are documented here: http://www.php.net/manual/en/function.pack.php

answered Jul 31, 2013 at 6:38

Joni

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2 Comments

BlackRoot Over a year ago

Thanks Joni but when in execute this code i get an array with one element only the solution below from Orangepill is so wonderfull and get all element in my file i'm use this code: ` $filename = "myFile.sav"; $handle = fopen($filename, "rb"); $fsize = filesize($filename); $contents = fread($handle, $fsize); $out = unpack("N", $contents); print_r($out); ` this code return one element only

Joni Over a year ago

If your file has packed ints all the way to the end and not just one you can use the asterix * formatting code to get them all. Or you can add a number to indicate how many ints should be read. This is all documented on the linked page.

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