Create UTF-16 (LE - BOM) file in PHP

I want to create a file in PHP with the following conditions:

1. Generate a file with a combination of String values received from Input Boxes and Hex values side by side
2. Hex value should be UTF-16 (LE) (BOM).

More information:

• I want to receive values from the user through input boxes, for example name, last name, age and score
• The value of age and score should be converted into Hex UTF-16 (BOM) and stored with the values of name and... which are of String type in a file with any extension, it doesn't matter (for example, of TXT type).

Let me give an example:

Score = 64
Name = Jack
Last Name = Saliv
Age = 21

By default, this file is generated as follows:

64JackSaliv21
And the Hex value becomes this value:
36344A61636B53616C69763231

But I want to get the following value:

䃿JackSaliｶ
And the Hex value is:
FFFEFF404A00610063006B00530061006C00690076FFFEFF15

.

In the following topics, I didn't get the results I wanted!

• https://stackoverflow.com/questions/19593637/how-do-i-write-utf-8-data-to-a-utf-16le-file-using-php
• https://stackoverflow.com/questions/23848601/encode-file-in-utf-16le-in-php-with-byte-order-mask-bom
• https://stackoverflow.com/questions/48099897/php-save-file-as-utf-8-without-bom

Reading through your Delph questions, along with your comments, I really don't fully understand what all this is supposed to do. However, given the input data along with the output, I can at least get pretty close, and exact with some additional corrections.

Basically, you can use mb_convert_encoding to get UTF-16LE, and then you can get the bytes as hex strings using unpack. To convert the decimal numbers to hex strings, just use dechex.

From your sample, I'm not certain why the decimal number 64 when converted to the hex string 40 is written as FF 40 and not just 40 or 40 00, but the $finalStringWithNumbersPadded variable has the FF appended. If the age or score were greater than 255 I'm not really sure what to do since FF is 1111 1111 and completely full.

Also, I'm assuming you have a typo in your expected bytes, the character for the last name should by 76 00 and not just 76.

Hopefully the code speaks for itself:

$score = 64;
$firstName = 'Jack';
$lastName = 'Saliv';
$age = 21;

$expected = 'FFFEFF404A00610063006B00530061006C00690076FFFEFF15';
$expectedCorrected = 'FFFEFF404A00610063006B00530061006C0069007600FFFEFF15';

// Convert to UTF-16LE and get hex, https://stackoverflow.com/a/16080439/231316
$nameAsUtf16LE = unpack('H*', mb_convert_encoding($firstName.$lastName, 'UTF-16LE', 'UTF-8'));

// UTF-16LE BOM
$utf16LeBom = 'FFFE';

// Convert to hex strings
$scoreAsHex = dechex($score);
$ageAsHex = dechex($age);

$finalString = sprintf(
    '%1$s%2$s%3$s',
    $utf16LeBom.$scoreAsHex,
    strtoupper($nameAsUtf16LE[1]), // This is 1-based, not 0-based
    $utf16LeBom.$ageAsHex,
);

$numberPadding = 'FF';
$finalStringWithNumbersPadded = sprintf(
    '%1$s%2$s%3$s',
    $utf16LeBom.$numberPadding.$scoreAsHex,
    strtoupper($nameAsUtf16LE[1]), // This is 1-based, not 0-based
    $utf16LeBom.$numberPadding.$ageAsHex,
);

echo 'Calculated         : '.$finalString;
echo PHP_EOL;
echo 'Padded             : '.$finalStringWithNumbersPadded;
echo PHP_EOL;
echo 'Expected           : '.$expected;
echo PHP_EOL;
echo 'Expected Corrected : '.$expectedCorrected;

assert($finalStringWithNumbersPadded === $expectedCorrected);

/* Output:
Calculated         : FFFE404A00610063006B00530061006C0069007600FFFE15
Padded             : FFFEFF404A00610063006B00530061006C0069007600FFFEFF15
Expected           : FFFEFF404A00610063006B00530061006C00690076FFFEFF15
Expected Corrected : FFFEFF404A00610063006B00530061006C0069007600FFFEFF15
*/

Demo: https://3v4l.org/XTdjA#v8.2.6

Edit

To write a string of hex characters to disk as binary data you can use pack:

$bindata = pack('H*', 'FFFEFF404A00610063006B00530061006C0069007600FFFEFF15');
file_put_contents('testing.data', $bindata);