Measure String Size in Bytes in PHP

Measure string size in Bytes in php

You have to figure out if the string is ascii encoded or encoded with a multi-byte format.

In the former case, you can just use strlen.

In the latter case you need to find the number of bytes per character.

the strlen documentation gives an example of how to do it : http://www.php.net/manual/en/function.strlen.php#72274

Byte size of string in PHP

This does essentially the same thing as Dany's answer, but a little more compact.

function human_filesize($bytes, $decimals = 2) {
    $size = array('B','kB','MB','GB','TB','PB','EB','ZB','YB');
    $factor = floor((strlen($bytes) - 1) / 3);
    return sprintf("%.{$decimals}f", $bytes / pow(1024, $factor)) . @$size[$factor];
}

echo human_filesize(filesize($filename));

Source: http://jeffreysambells.com/2012/10/25/human-readable-filesize-php

How to get the size of the content of a variable in PHP

$start_memory = memory_get_usage();
$foo = "Some variable";
echo memory_get_usage() - $start_memory;

This is good if you are working with any type of var.

What the correct way to get size of binary data in php?

As stated in the PHP manual, strlen returns the number of bytes in the string, not the character length.

In PHP, a null byte in a string does NOT count as the end of the string, and any null bytes are included in the length of the string.

So strlen can be used for binary data, no matter if the data is from a file or some other source.

String length in bytes in JavaScript

There is no way to do it in JavaScript natively. (See Riccardo Galli's answer for a modern approach.)

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For historical reference or where TextEncoder APIs are still unavailable.

If you know the character encoding, you can calculate it yourself though.

encodeURIComponent assumes UTF-8 as the character encoding, so if you need that encoding, you can do,

function lengthInUtf8Bytes(str) {
  // Matches only the 10.. bytes that are non-initial characters in a multi-byte sequence.
  var m = encodeURIComponent(str).match(/%[89ABab]/g);
  return str.length + (m ? m.length : 0);
}

This should work because of the way UTF-8 encodes multi-byte sequences. The first encoded byte always starts with either a high bit of zero for a single byte sequence, or a byte whose first hex digit is C, D, E, or F. The second and subsequent bytes are the ones whose first two bits are 10. Those are the extra bytes you want to count in UTF-8.

The table in wikipedia makes it clearer

Bits        Last code point Byte 1          Byte 2          Byte 3
  7         U+007F          0xxxxxxx
 11         U+07FF          110xxxxx        10xxxxxx
 16         U+FFFF          1110xxxx        10xxxxxx        10xxxxxx
...

If instead you need to understand the page encoding, you can use this trick:

function lengthInPageEncoding(s) {
  var a = document.createElement('A');
  a.href = '#' + s;
  var sEncoded = a.href;
  sEncoded = sEncoded.substring(sEncoded.indexOf('#') + 1);
  var m = sEncoded.match(/%[0-9a-f]{2}/g);
  return sEncoded.length - (m ? m.length * 2 : 0);
}

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