I wanted a function that returned filesizes like Windows does, and surprisingly I could find none at all. Even worse, some here and elsewhere are broken in that they assume 1KB = 1000B.
So I coded one! Plus two helper functions. Here they are:
// Returns a size in a human-readable form from a byte count.
function humanSize($bytes)
{
if ($bytes < 1024) return "$bytes Bytes";
$units = ['KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];
foreach ($units as $i => $unit)
{
// The reason for this threshold is to avoid e.g., "1000 KB",
// instead jumping from e.g., "999 KB" to "0.97 MB".
$multiplier = pow(1024, $i + 1);
$threshold = $multiplier * 1000;
if ($bytes < $threshold)
{
$size = formatToMinimumDigits($bytes / $multiplier, false);
return "$size $unit";
}
}
}
// Efficiently calculates how many digits the integer portion of a number has.
function digits($number)
{
// Yes, I could convert to string and count the characters,
// but this is faster and cooler.
$log = log10($number);
if ($log < 0) return 1;
return floor($log) + 1;
}
// Formats a number to a minimum amount of digits.
// In other words, makes sure that a number has at least $digits on it, even if
// that means introducing redundant decimal zeroes at the end, or rounding the
// ones present exceeding the $digits count when combined with the integers.
// For example:
// formatToMinimumDigits(10) // 10.0
// formatToMinimumDigits(1.1) // 1.10
// formatToMinimumDigits(12.34) // 12.3
// formatToMinimumDigits(1.234) // 1.23
// formatToMinimumDigits(1.203) // 1.20
// formatToMinimumDigits(123.4) // 123
// formatToMinimumDigits(100) // 100
// formatToMinimumDigits(1000) // 1000
// formatToMinimumDigits(1) // 1.00
// formatToMinimumDigits(1.002) // 1.00
// formatToMinimumDigits(1.005) // 1.01
// formatToMinimumDigits(1.005, false) // 1.00
// This is primarily useful for generating human-friendly numbers.
function formatToMinimumDigits($value, $round = true, $digits = 3)
{
$integers = floor($value);
$decimalsNeeded = $digits - digits($integers);
if ($decimalsNeeded < 1)
{
return $integers;
}
else
{
if ($round)
{
// This relies on implicit type casting of float to string.
$parts = explode('.', round($value, $decimalsNeeded));
// We re-declare the integers because they may change
// after we round the number.
$integers = $parts[0];
}
else
{
// Again, implicit type cast to string.
$parts = explode('.', $value);
}
// And because of the implicit type cast, we must guard against
// 1.00 becoming 1, thus not exploding the second half of it.
$decimals = isset($parts[1]) ? $parts[1] : '0';
$joined = "$integers.$decimals".str_repeat('0', $digits);
return substr($joined, 0, $digits + 1);
}
}
Usage is as simple as humanSize(123456789).
$unit == "GB" || !$unit && $size >= 1<<30. – Idoux