VersionPress\Utils\StringUtils::substringFromTo PHP Method

    public static function substringFromTo($str, $from, $to)
    {
        return substr($str, $from, $to - $from);
    }

 /**
  * Transforms PHP primitives, arrays, objects etc. to INI. Complex structures like arrays and objects
  * can take multiple lines (every scalar value is on new line).
  *
  * @return array
  */
 private static function parseSerializedString()
 {
     $type = self::$value[self::$index];
     self::$index += 2;
     // <type>:
     switch ($type) {
         case 's':
             $length = intval(StringUtils::substringFromTo(self::$value, self::$index, strpos(self::$value, ':', self::$index)));
             self::$index += strlen($length) + 2;
             // :"
             $str = substr(self::$value, self::$index, $length);
             self::$index += strlen($str) + 2;
             // ";
             return ['type' => 'string', 'value' => $str];
         case 'i':
             $number = StringUtils::substringFromTo(self::$value, self::$index, strpos(self::$value, ';', self::$index));
             self::$index += strlen($number) + 1;
             // ;
             return ['type' => 'int', 'value' => intval($number)];
         case 'd':
             $number = StringUtils::substringFromTo(self::$value, self::$index, strpos(self::$value, ';', self::$index));
             self::$index += strlen($number) + 1;
             // ;
             return ['type' => 'double', 'value' => doubleval($number)];
         case 'b':
             $strVal = StringUtils::substringFromTo(self::$value, self::$index, strpos(self::$value, ';', self::$index));
             self::$index += 2;
             // <0|1>;
             return ['type' => 'boolean', 'value' => $strVal === '1'];
         case 'a':
             $length = intval(StringUtils::substringFromTo(self::$value, self::$index, strpos(self::$value, ':', self::$index)));
             self::$index += strlen($length) + 2;
             // :{
             $subItems = [];
             for ($i = 0; $i < $length; $i++) {
                 $key = self::parseSerializedString()['value'];
                 $value = self::parseSerializedString();
                 $subItems[$key] = $value;
             }
             self::$index += 1;
             // }
             return ['type' => 'array', 'value' => $subItems];
         case 'O':
             $classNameLength = intval(StringUtils::substringFromTo(self::$value, self::$index, strpos(self::$value, ':', self::$index)));
             self::$index += strlen($classNameLength) + 2;
             // :"
             $className = substr(self::$value, self::$index, $classNameLength);
             self::$index += $classNameLength + 2;
             // ":
             $attributeCount = intval(StringUtils::substringFromTo(self::$value, self::$index, strpos(self::$value, ':', self::$index)));
             self::$index += strlen($attributeCount) + 2;
             // :{
             $attribute = [];
             for ($i = 0; $i < $attributeCount; $i++) {
                 $attributeName = self::parseSerializedString()['value'];
                 $attributeName = str_replace("*", '*', $attributeName);
                 $attributeName = str_replace("{$className}", '-', $attributeName);
                 $attributeValue = self::parseSerializedString();
                 $attribute[$attributeName] = $attributeValue;
             }
             self::$index += 1;
             // }
             return ['type' => 'object', 'class' => $className, 'value' => $attribute];
         case 'N':
             return ['type' => 'null'];
         case 'r':
         case 'R':
             $number = StringUtils::substringFromTo(self::$value, self::$index, strpos(self::$value, ';', self::$index));
             self::$index += strlen($number) + 1;
             // ;
             return ['type' => $type === 'r' ? '*pointer*' : '*reference*', 'value' => intval($number)];
         default:
             return [];
     }
 }