【PHP内核学习】变量跟数据类型

【PHP内核学习】变量和数据类型

<div class="line" id="LC1" style="padding-left:10px; height:18px">|=-----------------------------------------------------------------------=|<div class="line" id="LC2" style="padding-left:10px; height:18px">|=---------------------=[ PHP内核中的变量和数据类型]=--------------------=|<div class="line" id="LC3" style="padding-left:10px; height:18px">|=-----------------------------------------------------------------------=|<div class="line" id="LC4" style="padding-left:10px; height:18px">|=--------------------------=[ by d4shman ]=-----------------------------=|<div class="line" id="LC5" style="padding-left:10px; height:18px">|=-----------------------------------------------------------------------=|<div class="line" id="LC6" style="padding-left:10px; height:18px">|=-------------------------=[  May 6, 2014  ]=---------------------------=|<div class="line" id="LC7" style="padding-left:10px; height:18px">|=-----------------------------------------------------------------------=|<div class="line" id="LC8" style="padding-left:10px; height:18px">
<br ><div class="line" id="LC9" style="padding-left:10px; height:18px">(_____ \| |   | (_____ \   /\   / _____) |  / )   <div class="line" id="LC10" style="padding-left:10px; height:18px"> _____) ) |__ | |_____) ) /  \ | /     | | / /    <div class="line" id="LC11" style="padding-left:10px; height:18px">|  ____/|  __)| (_____ ( / /\ \| |     | |<div class="line" id="LC12" style="padding-left:10px; height:18px">| |     | |   | |     | | |__| | \_____| | \ \    <div class="line" id="LC13" style="padding-left:10px; height:18px">|_|     |_|   |_|     |_|______|\______)_|  \_)   (向phrack致敬!)<div class="line" id="LC14" style="padding-left:10px; height:18px">
<br ><div class="line" id="LC15" style="padding-left:10px; height:18px"><div class="line" id="LC16" style="padding-left:10px; height:18px">
<br ><div class="line" id="LC17" style="padding-left:10px; height:18px"> 0x01  变量的结构和类型<div class="line" id="LC18" style="padding-left:10px; height:18px"> 0x02  哈希表--PHP的灵魂<div class="line" id="LC19" style="padding-left:10px; height:18px"> 0x03  常量<div class="line" id="LC20" style="padding-left:10px; height:18px"> 0x04  参考文献<div class="line" id="LC21" style="padding-left:10px; height:18px"><div class="line" id="LC22" style="padding-left:10px; height:18px">
<br ><div class="line" id="LC23" style="padding-left:10px; height:18px">/////<div class="line" id="LC24" style="padding-left:10px; height:18px">0x01  变量的结构和类型<div class="line" id="LC25" style="padding-left:10px; height:18px">/////<div class="line" id="LC26" style="padding-left:10px; height:18px">1.数据类型<div class="line" id="LC27" style="padding-left:10px; height:18px">  1.1静态类型语言（C/Java）,编译时确定<div class="line" id="LC28" style="padding-left:10px; height:18px">  1.2动态类型语言（php/python）,运行时确定<div class="line" id="LC29" style="padding-left:10px; height:18px">  1.3无类型语言(汇编)，操作的底层存储<div class="line" id="LC30" style="padding-left:10px; height:18px">
<br ><div class="line" id="LC31" style="padding-left:10px; height:18px">2.php内核中所有的变量使用同一种数据结构zval来保存，而这个结构同时表示php中各种数据类型，它不仅仅包含变量的值，也包含变量的类型。这就是php弱类型的核心。<div class="line" id="LC32" style="padding-left:10px; height:18px">        php中的8中数据类型：<div class="line" id="LC33" style="padding-left:10px; height:18px">  2.1标量类型： boolean, integer, float, string<div class="line" id="LC34" style="padding-left:10px; height:18px">  2.2复合类型:  array, object<div class="line" id="LC35" style="padding-left:10px; height:18px">  2.3特殊类型： resource, null<div class="line" id="LC36" style="padding-left:10px; height:18px">  <div class="line" id="LC37" style="padding-left:10px; height:18px">3.zval结构体(在php源码目录下Zend/zend.h中定义)：<div class="line" id="LC38" style="padding-left:10px; height:18px">  struct _zval_struct｛<div class="line" id="LC39" style="padding-left:10px; height:18px">  	  /*Variable information*/<div class="line" id="LC40" style="padding-left:10px; height:18px">  	  zvalue_value value  	/*value， 变量的值*/<div class="line" id="LC41" style="padding-left:10px; height:18px">  	  zend_uint refcount__gc  /*reference count， 引用计数器*/<div class="line" id="LC42" style="padding-left:10px; height:18px">  	  zend_uchar type 		/*active type， 变量的类型*/<div class="line" id="LC43" style="padding-left:10px; height:18px">  	  zend_uchar is_ref__gc;  /*变量是否被引用*/<div class="line" id="LC44" style="padding-left:10px; height:18px">  ｝<div class="line" id="LC45" style="padding-left:10px; height:18px">
<br ><div class="line" id="LC46" style="padding-left:10px; height:18px">4.变量类型：<div class="line" id="LC47" style="padding-left:10px; height:18px">  /*data types */<div class="line" id="LC48" style="padding-left:10px; height:18px">  #define IS_NULL		0 <div class="line" id="LC49" style="padding-left:10px; height:18px">  #define IS_LONG 		1<div class="line" id="LC50" style="padding-left:10px; height:18px">  #define IS_DOUBLE 	2<div class="line" id="LC51" style="padding-left:10px; height:18px">  #define IS_BOOL 		3<div class="line" id="LC52" style="padding-left:10px; height:18px">  #define IS_ARRAY		4<div class="line" id="LC53" style="padding-left:10px; height:18px">  #define IS_OBJECT		5<div class="line" id="LC54" style="padding-left:10px; height:18px">  #define IS_STRING 	6<div class="line" id="LC55" style="padding-left:10px; height:18px">  #define IS_RESOURCE	7<div class="line" id="LC56" style="padding-left:10px; height:18px">  #define IS_CONSTANT	8<div class="line" id="LC57" style="padding-left:10px; height:18px">  #define IS_CONSTANT_ARRAY	9<div class="line" id="LC58" style="padding-left:10px; height:18px">  #define IS_CALLABLE	10<div class="line" id="LC59" style="padding-left:10px; height:18px">  <div class="line" id="LC60" style="padding-left:10px; height:18px">5.变量的值存储<div class="line" id="LC61" style="padding-left:10px; height:18px">  typedef union _zvalue_value {<div class="line" id="LC62" style="padding-left:10px; height:18px">      long lval; 		/*long、bool、resource类型*/<div class="line" id="LC63" style="padding-left:10px; height:18px">	  double dval ;	/*double 类型*/<div class="line" id="LC64" style="padding-left:10px; height:18px">	  struct {		/*string 类型, len保存了字符串的长度*/<div class="line" id="LC65" style="padding-left:10px; height:18px">	  	char *val;<div class="line" id="LC66" style="padding-left:10px; height:18px">	  	int len;<div class="line" id="LC67" style="padding-left:10px; height:18px">	  } str;<div class="line" id="LC68" style="padding-left:10px; height:18px">	  HashTable *ht;  /*数组, 用HashTable实现*/<div class="line" id="LC69" style="padding-left:10px; height:18px">	  zend_object_value obj; /*object 类型*/<div class="line" id="LC70" style="padding-left:10px; height:18px">  } zvalue_value;<div class="line" id="LC71" style="padding-left:10px; height:18px">  <div class="line" id="LC72" style="padding-left:10px; height:18px">  这里之所以用共同体(union)是因为一个变量只可能有一种类型，符合共同体的特性，如果使用结构体则会浪费内存。<div class="line" id="LC73" style="padding-left:10px; height:18px">  <div class="line" id="LC74" style="padding-left:10px; height:18px">  实例：创建一个值为10的整型变量lvar,用php脚本的话很简单，就是:$lvar = 10<div class="line" id="LC75" style="padding-left:10px; height:18px">  而PHP内核中的实现可能就是类似下面这样：<div class="line" id="LC76" style="padding-left:10px; height:18px">  zval lval;<div class="line" id="LC77" style="padding-left:10px; height:18px">  Z_TYPE(lvar) = IS_LONG;<div class="line" id="LC78" style="padding-left:10px; height:18px">  Z_LVAL(lvar) = 10;<div class="line" id="LC79" style="padding-left:10px; height:18px">  <div class="line" id="LC80" style="padding-left:10px; height:18px">/////<div class="line" id="LC81" style="padding-left:10px; height:18px">0x02  哈希表--PHP的灵魂<div class="line" id="LC82" style="padding-left:10px; height:18px">/////<div class="line" id="LC83" style="padding-left:10px; height:18px">1.为什么用哈希表<div class="line" id="LC84" style="padding-left:10px; height:18px">  哈希表通常提供CRUD(Create, Read, Update, Delete)操作，设计合理的哈希表中，这些操作时间复杂度为O(1)，这也是它被钟爱的原因。<div class="line" id="LC85" style="padding-left:10px; height:18px">  hash(key) -> index<div class="line" id="LC86" style="padding-left:10px; height:18px">  <div class="line" id="LC87" style="padding-left:10px; height:18px">2.哈希表的实现：结构体 bucket和_hashtable组成了完整的HashTable。<div class="line" id="LC88" style="padding-left:10px; height:18px">  首先看bucket结构体(定义在 Zend/zend_hash.h):<div class="line" id="LC89" style="padding-left:10px; height:18px">  typedef struct bucket {<div class="line" id="LC90" style="padding-left:10px; height:18px">	  ulong h;  					/*hash值*/<div class="line" id="LC91" style="padding-left:10px; height:18px">	  uint nKeyLength;			/*key的长度*/<div class="line" id="LC92" style="padding-left:10px; height:18px">	  void *pData;				/*要保存的内存块地址，通常是malloc来的地址*/<div class="line" id="LC93" style="padding-left:10px; height:18px">	  void *pDataPtr;				/*保存指针数据，不经过malloc的指针，防止产生内存碎片*/<div class="line" id="LC94" style="padding-left:10px; height:18px">	  struct bucket *pListNext;   /*bucket中具有同一hash值的下一个元素*/<div class="line" id="LC95" style="padding-left:10px; height:18px">	  struct bucket *pListLast;   /*bucket中具有同一hash值的上一个元素*/<div class="line" id="LC96" style="padding-left:10px; height:18px">	  struct bucket *pNext;		/*双向链表的下一个元素*/<div class="line" id="LC97" style="padding-left:10px; height:18px">	  struct bucket *pLast;       /*双向链表的上一个元素*/<div class="line" id="LC98" style="padding-left:10px; height:18px">	  const char *arKey;			/*保存key*/<div class="line" id="LC99" style="padding-left:10px; height:18px">  } Bucket;<div class="line" id="LC100" style="padding-left:10px; height:18px">  <div class="line" id="LC101" style="padding-left:10px; height:18px">  可以看出bucket是一个双向链表，这是为了解决多个key冲突的问题(即算法导论中的链接法)<div class="line" id="LC102" style="padding-left:10px; height:18px">  <div class="line" id="LC103" style="padding-left:10px; height:18px">  <div class="line" id="LC104" style="padding-left:10px; height:18px">  再看_hashtable结构体：<div class="line" id="LC105" style="padding-left:10px; height:18px">  typedef struct _hashtable {<div class="line" id="LC106" style="padding-left:10px; height:18px">      uint nTableSize;                /*bucket数组的大小*/<div class="line" id="LC107" style="padding-left:10px; height:18px">	  uint nTableMask;				<div class="line" id="LC108" style="padding-left:10px; height:18px">	  uint nNumOfElements;			/*HashTable中元素的个数*/<div class="line" id="LC109" style="padding-left:10px; height:18px">	  ulong nNextFreeElement;			/*下一个可用的Bucket位置*/<div class="line" id="LC110" style="padding-left:10px; height:18px">	  Bucket *pInternalPointer		/*遍历HashTable元素*/<div class="line" id="LC111" style="padding-left:10px; height:18px">	  Bucket *pListHead;				/*双向链表表头*/<div class="line" id="LC112" style="padding-left:10px; height:18px">	  Bucket *pListTail;				/*双向链表表尾*/<div class="line" id="LC113" style="padding-left:10px; height:18px">	  Bucket **arBuckets;				/*Bucket数组*/<div class="line" id="LC114" style="padding-left:10px; height:18px">  } HashTable;<div class="line" id="LC115" style="padding-left:10px; height:18px">  <div class="line" id="LC116" style="padding-left:10px; height:18px">  ========<div class="line" id="LC117" style="padding-left:10px; height:18px">  此处为HashTable的结构图<div class="line" id="LC118" style="padding-left:10px; height:18px">  ========<div class="line" id="LC119" style="padding-left:10px; height:18px">
<br ><div class="line" id="LC120" style="padding-left:10px; height:18px">3.神奇的数字--33<div class="line" id="LC121" style="padding-left:10px; height:18px">  见我原来的一篇博客：http://blog.csdn.net/wusuopubupt/article/details/11479869<div class="line" id="LC122" style="padding-left:10px; height:18px">  下面是PHP源码中的一段注释：<div class="line" id="LC123" style="padding-left:10px; height:18px">  /*<div class="line" id="LC124" style="padding-left:10px; height:18px">   * DJBX33A (Daniel J. Bernstein, Times 33 with Addition)<div class="line" id="LC125" style="padding-left:10px; height:18px">   *<div class="line" id="LC126" style="padding-left:10px; height:18px">   * This is Daniel J. Bernstein's popular `times 33' hash function as<div class="line" id="LC127" style="padding-left:10px; height:18px">   * posted by him years ago on comp.lang.c. It basically uses a function<div class="line" id="LC128" style="padding-left:10px; height:18px">   * like ``hash(i) = hash(i-1) * 33 + str[i]''. This is one of the best<div class="line" id="LC129" style="padding-left:10px; height:18px">   * known hash functions for strings. Because it is both computed very<div class="line" id="LC130" style="padding-left:10px; height:18px">   * fast and distributes very well.<div class="line" id="LC131" style="padding-left:10px; height:18px">   *<div class="line" id="LC132" style="padding-left:10px; height:18px">   * The magic of number 33, i.e. why it works better than many other<div class="line" id="LC133" style="padding-left:10px; height:18px">   * constants, prime or not, has never been adequately explained by<div class="line" id="LC134" style="padding-left:10px; height:18px">   * anyone. So I try an explanation: if one experimentally tests all<div class="line" id="LC135" style="padding-left:10px; height:18px">   * multipliers between 1 and 256 (as RSE did now) one detects that even<div class="line" id="LC136" style="padding-left:10px; height:18px">   * numbers are not useable at all. The remaining 128 odd numbers<div class="line" id="LC137" style="padding-left:10px; height:18px">   * (except for the number 1) work more or less all equally well. They<div class="line" id="LC138" style="padding-left:10px; height:18px">   * all distribute in an acceptable way and this way fill a hash table<div class="line" id="LC139" style="padding-left:10px; height:18px">   * with an average percent of approx. 86%.<div class="line" id="LC140" style="padding-left:10px; height:18px">   *<div class="line" id="LC141" style="padding-left:10px; height:18px">   * If one compares the Chi^2 values of the variants, the number 33 not<div class="line" id="LC142" style="padding-left:10px; height:18px">   * even has the best value. But the number 33 and a few other equally<div class="line" id="LC143" style="padding-left:10px; height:18px">   * good numbers like 17, 31, 63, 127 and 129 have nevertheless a great<div class="line" id="LC144" style="padding-left:10px; height:18px">   * advantage to the remaining numbers in the large set of possible<div class="line" id="LC145" style="padding-left:10px; height:18px">   * multipliers: their multiply operation can be replaced by a faster<div class="line" id="LC146" style="padding-left:10px; height:18px">   * operation based on just one shift plus either a single addition<div class="line" id="LC147" style="padding-left:10px; height:18px">   * or subtraction operation. And because a hash function has to both<div class="line" id="LC148" style="padding-left:10px; height:18px">   * distribute good _and_ has to be very fast to compute, those few<div class="line" id="LC149" style="padding-left:10px; height:18px">   * numbers should be preferred and seems to be the reason why Daniel J.<div class="line" id="LC150" style="padding-left:10px; height:18px">   * Bernstein also preferred it.<div class="line" id="LC151" style="padding-left:10px; height:18px">   *<div class="line" id="LC152" style="padding-left:10px; height:18px">   *<div class="line" id="LC153" style="padding-left:10px; height:18px">   *                  -- Ralf S. Engelschall <div class="line" id="LC154" style="padding-left:10px; height:18px">   */<div class="line" id="LC155" style="padding-left:10px; height:18px">
<br ><div class="line" id="LC156" style="padding-left:10px; height:18px">  <div class="line" id="LC157" style="padding-left:10px; height:18px">4.哈希表的操作接口(省略了部分参数)<div class="line" id="LC158" style="padding-left:10px; height:18px">  初始化HashTable：int _zend_hash_init(HashTable *ht, uint nSize, hash_func_t pHashFunction);<div class="line" id="LC159" style="padding-left:10px; height:18px">  添加新hash值：   int _zend_hash_add_or_update(HashTable *ht, const char *arKey, uint nKeyLength, void *pData)<div class="line" id="LC160" style="padding-left:10px; height:18px">  查找hash：       int zend_hash_find(const HashTable *ht, const char *arKey, uint nKeyLength, void **pData);<div class="line" id="LC161" style="padding-left:10px; height:18px">
<br ><div class="line" id="LC162" style="padding-left:10px; height:18px">
<br ><div class="line" id="LC163" style="padding-left:10px; height:18px">/////<div class="line" id="LC164" style="padding-left:10px; height:18px">0x03  常量<div class="line" id="LC165" style="padding-left:10px; height:18px">///// <div class="line" id="LC166" style="padding-left:10px; height:18px">1.常量的内部结构<div class="line" id="LC167" style="padding-left:10px; height:18px">  typedef struct _zend_constant {<div class="line" id="LC168" style="padding-left:10px; height:18px">	  zval value;<div class="line" id="LC169" style="padding-left:10px; height:18px">	  int flags;  /*常量标记，如 CONST_PERSISTENT | CONST_CS */<div class="line" id="LC170" style="padding-left:10px; height:18px">	  char *name;<div class="line" id="LC171" style="padding-left:10px; height:18px">	  uint name_len;<div class="line" id="LC172" style="padding-left:10px; height:18px">	  int module_number;<div class="line" id="LC173" style="padding-left:10px; height:18px">  } zend_constant;<div class="line" id="LC174" style="padding-left:10px; height:18px">
<br ><div class="line" id="LC175" style="padding-left:10px; height:18px">2.define定义常量的过程  <div class="line" id="LC176" style="padding-left:10px; height:18px">  define的实现(定义在Zend/zend_builtin_functions.c)，下面是部分核心代码：<div class="line" id="LC177" style="padding-left:10px; height:18px">  <div class="line" id="LC178" style="padding-left:10px; height:18px">  ZEND_FUNCTION(define)<div class="line" id="LC179" style="padding-left:10px; height:18px">  {<div class="line" id="LC180" style="padding-left:10px; height:18px">      /* 检查常量名是否存在 */<div class="line" id="LC181" style="padding-left:10px; height:18px">      if (zend_memnstr(name, "::", sizeof("::") - 1, name + name_len)) {<div class="line" id="LC182" style="padding-left:10px; height:18px">          zend_error(E_WARNING, "Class constants cannot be defined or redefined");<div class="line" id="LC183" style="padding-left:10px; height:18px">          RETURN_FALSE;<div class="line" id="LC184" style="padding-left:10px; height:18px">      }<div class="line" id="LC185" style="padding-left:10px; height:18px">      <div class="line" id="LC186" style="padding-left:10px; height:18px">      ... // 类常量定义 此处不做介绍<div class="line" id="LC187" style="padding-left:10px; height:18px">      <div class="line" id="LC188" style="padding-left:10px; height:18px">      c.value = *val;<div class="line" id="LC189" style="padding-left:10px; height:18px">      zval_copy_ctor(&c.value);<div class="line" id="LC190" style="padding-left:10px; height:18px">      if (val_free) {<div class="line" id="LC191" style="padding-left:10px; height:18px">              zval_ptr_dtor(&val_free);<div class="line" id="LC192" style="padding-left:10px; height:18px">      }<div class="line" id="LC193" style="padding-left:10px; height:18px">      c.flags = case_sensitive;  /* 大小写敏感 */<div class="line" id="LC194" style="padding-left:10px; height:18px">      c.name = zend_strndup(name, name_len);<div class="line" id="LC195" style="padding-left:10px; height:18px">      c.name_len = name_len+1;<div class="line" id="LC196" style="padding-left:10px; height:18px">      c.module_number = PHP_USER_CONSTANT;<div class="line" id="LC197" style="padding-left:10px; height:18px">      if (zend_register_constant(&c TSRMLS_CC) == SUCCESS) {  /*注册常量*/<div class="line" id="LC198" style="padding-left:10px; height:18px">              RETURN_TRUE;<div class="line" id="LC199" style="padding-left:10px; height:18px">      } else {<div class="line" id="LC200" style="padding-left:10px; height:18px">              RETURN_FALSE;<div class="line" id="LC201" style="padding-left:10px; height:18px">      }<div class="line" id="LC202" style="padding-left:10px; height:18px">  }<div class="line" id="LC203" style="padding-left:10px; height:18px">  <div class="line" id="LC204" style="padding-left:10px; height:18px">3.魔术常量<div class="line" id="LC205" style="padding-left:10px; height:18px">  PHP中的魔术常量，虽然叫做常量，但它们的值实际上随它们在代码中的位置而变化的。<div class="line" id="LC206" style="padding-left:10px; height:18px">  __LINE__	 	文件中的当前行号。<div class="line" id="LC207" style="padding-left:10px; height:18px">  __FILE__	 	文件的完整路径和文件名。如果用在被包含文件中，则返回被包含的文件名。<div class="line" id="LC208" style="padding-left:10px; height:18px">  __DIR__	 	文件所在的目录。如果用在被包括文件中，则返回被包括的文件所在的目录。它等价于 dirname(__FILE__)。<div class="line" id="LC209" style="padding-left:10px; height:18px">  __FUNCTION__	函数名称<div class="line" id="LC210" style="padding-left:10px; height:18px">  __CLASS__	 	类的名称。类名包括其被声明的作用区域（例如 Foo\Bar）。<div class="line" id="LC211" style="padding-left:10px; height:18px">  __TRAIT__	 	Trait 的名字。Trait 名包括其被声明的作用区域（例如 Foo\Bar）。<div class="line" id="LC212" style="padding-left:10px; height:18px">  __METHOD__	类的方法名<div class="line" id="LC213" style="padding-left:10px; height:18px">  __NAMESPACE__	当前命名空间的名称（区分大小写）。此常量是在编译时定义的（PHP 5.3.0 新增）。<div class="line" id="LC214" style="padding-left:10px; height:18px">  <div class="line" id="LC215" style="padding-left:10px; height:18px">  PHP内核会在词法解析时将这些常量的内容赋值进行替换，而不是在运行时进行分析。 举个例子：<div class="line" id="LC216" style="padding-left:10px; height:18px">  <?php </p><div class="line" id="LC217" style="padding-left:10px; height:18px">  echo __LINE__;<div class="line" id="LC218" style="padding-left:10px; height:18px">  function demo() {<div class="line" id="LC219" style="padding-left:10px; height:18px">    echo __FUNCTION__;<div class="line" id="LC220" style="padding-left:10px; height:18px">  }<div class="line" id="LC221" style="padding-left:10px; height:18px">  demo();<div class="line" id="LC222" style="padding-left:10px; height:18px">  ?><div class="line" id="LC223" style="padding-left:10px; height:18px">  PHP已经在词法解析时将这些常量换成了对应的值，以上的代码可以看成如下的PHP代码：<div class="line" id="LC224" style="padding-left:10px; height:18px">  <?php </p><div class="line" id="LC225" style="padding-left:10px; height:18px">  echo 2;<div class="line" id="LC226" style="padding-left:10px; height:18px">  function demo() {<div class="line" id="LC227" style="padding-left:10px; height:18px">      echo "demo";<div class="line" id="LC228" style="padding-left:10px; height:18px">  }<div class="line" id="LC229" style="padding-left:10px; height:18px">  demo();<div class="line" id="LC230" style="padding-left:10px; height:18px">  ?><div class="line" id="LC231" style="padding-left:10px; height:18px">
<br ><div class="line" id="LC232" style="padding-left:10px; height:18px">  ===========<div class="line" id="LC233" style="padding-left:10px; height:18px">  此处涉及编译原理知识，需补充。<div class="line" id="LC234" style="padding-left:10px; height:18px">  ===========<div class="line" id="LC235" style="padding-left:10px; height:18px">  <div class="line" id="LC236" style="padding-left:10px; height:18px">/////<div class="line" id="LC237" style="padding-left:10px; height:18px">0x04  参考文献<div class="line" id="LC238" style="padding-left:10px; height:18px">///// <div class="line" id="LC239" style="padding-left:10px; height:18px">
<br ><div class="line" id="LC240" style="padding-left:10px; height:18px">TIPI: http://www.php-internals.com/book/?p=chapt03/03-00-variable-and-data-types<dl class="comment_item comment_topic">
<dt class="comment_head">1楼<span class="user">wusuopuBUPT<span class="ptime">昨天 14:06</span></span>
</dt>
<dd class="comment_body">本文github地址：https://github.com/wusuopubupt/phpLib/blob/master/PHP%E5%86%85%E6%A0%B8%E4%B8%AD%E7%9A%84%E5%8F%98%E9%87%8F%E5%92%8C%E6%95%B0%E6%8D%AE%E7%B1%BB%E5%9E%8B</dd>
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