typedef struct _zval_struct zval; 
   
  struct _zval_struct { 
    zvalue_value value; // 存储变量的值 
    zend_uint refcount__gc; // 表示引用计数 
    zend_uchar type;  // 变量具体的类型 
    zend_uchar is_ref_gc;  // 表示是否为引用 
  }; 

  typedef union _zvalue_value { 
    long lval; 
    double dval; 
    struct { 
      char *val; 
      int len; 
    } str; 
    HashTable *ht; 
    zend_object_value obj; 
  } _zvalue_value; 

 <?php 
   
  /** 
   * 求两个日期之间相差的天数(针对1970年1月1日之后，求之前可以采用泰勒公式) 
   * @param string $day1 
   * @param string $day2 
   * @return number 
   */ 
  function diffBetweenTwoDays ($day1, $day2) 
  { 
    $second1 = strtotime($day1); 
    $second2 = strtotime($day2); 
     
    if ($second1 < $second2) { 
      $tmp = $second2; 
      $second2 = $second1; 
      $second1 = $tmp; 
    } 
     
    return ($second1 - $second2) / 86400; 
  } 
   
  $day1 = "2013-07-27"; 
  $day2 = "2013-08-04"; 
   
  $diff = diffBetweenTwoDays($day1, $day2); 
  echo $diff."\n";