Read 8 bytes and cast it to double

jcgonz

I need to read 8 bytes from a binary file and cast this value to a double in order to save it in a database.

I think the problem is that fread translates it to a string, and floatval() only strips the string characters to leave the "float" value...

I read the file using C++ and it casts it perfectly, but in PHP I can't find the way to do it.

Thank you in advance!

mjlively

Most of the time you shouldn't have to do any type casting with a php variable as it is able to tell quite well what you are trying to do with the variable, but in the event that you are in one of those special situations, give this url a visit: http://www.php.net/manual/en/language.types.type-juggling.php#language.types.typecasting

That should give you the info you need to know

ednark

well... if you are truly dealing with raw binary data you can use the [man]unpack/man function...this should do things at the binary level and not at the php/string level...

i have a needless write i here just to get at what you were doing... you should be able to see the difference in the two values it prints out

<?php

header('Content-type: text/plain');

$data = pack( 'd', 2.22E2 );

$fp = fopen( './binread.data', 'a+' );
fwrite( $fp, $data );
fclose( $fp );


$fp  = fopen( './binread.data', 'r' );
$val = fread( $fp, 8 );
fclose( $fp );

$result     = unpack( 'd', $val );
$unpacked   = $result[NULL];
$typecast   = (double)$val; 

echo gettype($unpacked) ." : ". $unpacked ."\n";
echo gettype($typecast) ." : ". $typecast ."\n";

?>