azure-storage-common/src/Common/Internal/Utilities.php
public static function allZero($content)
    {
        $size = strlen($content);

        // If all Zero, skip this range
        for ($i = 0; $i < $size; $i++) {
            if (ord($content[$i]) != 0) {
                return false;
            }
        }

        return true;
    }
public static function allZero($content)
    {
        $size = strlen($content);

        // If all Zero, skip this range
        for ($i = 0; $i < $size; $i++) {
            if (ord($content[$i]) != 0) {
                return false;
            }
        }

        return true;
    }
Check if all the bytes are zero.

@param string $content The content.
@return bool