PHP 手册拾遗

var_dump(false and true);// 与   false
var_dump(false or true); // 或   true
var_dump(true xor false);// 异或 trueCopy

$smaller = 1 <=> 2;
$equal   = 1 <=> 1;
$lager   = 2 <=> 1;
var_dump($smaller);
var_dump($equal);
var_dump($lager);
//-1 小于 0等于 1 大于Copy

$equalOrSamller = (1 <=> 2) != 1;
$equalOrLager   = (1 <=> 2) != -1;
//小于等于 == 不大于 , 大于等于 == 不小于Copy

function defaultValue(&$var,$default){
  if(!isset($var))
    return $default;
  return $var;
}
$temp = defaultValue($temp,'a');Copy

$var = $args ?? 'default value';Copy

$opts = array(
  'http' =>array(
    'proxy' => null,
    'method' => null,
    'header' => null,
    'timeout' => null,
    'content' => null,
    'user_agent' => null,
    'max_redirects' => null,
    'ignore_errors' => null,
    'request_fulluri' => null,
    'follow_location' => null,
    'protocol_version' => null
  )
);

$context = stream_context_create($opts);
$result = file_get_contents('http://example.com/submit.php', false, $context);
//或者
$stream = fopen('http://example.com/submit.php', 'r', false, $context);
var_dump(stream_get_meta_data($stream));//响应报文的信息
var_dump(stream_get_contents($stream));
fclose($stream);Copy

stream_context_set_option($context,$opts);Copy

function genaretor(){
  $receive1 = yield 'send out 1';
  yield $receive1;
  $receive2 = yield 'send out 2';
  // var_dump($this);
  // $this->next();这样不行~就是说只能外部控制咯~
  //Fatal error: Uncaught Error: Using $this when not in object context
  yield $receive2;//入口和出口绑定一起了~可能有时候只想出,不想进~
}

$gen = genaretor();
var_dump($gen);//class Generator#4 (0) {}
var_export($gen);//Generator::__set_state(array()) , 记得魔术方法里面有__set_state()
$gen->rewind();
var_dump($gen->current());//send out 1

// $gen->next();
// $gen->rewind();
//Fatal error: Uncaught Exception: Cannot rewind a generator that was already run

var_dump($gen->send('send in 1'));//send in 1
var_dump($gen->current());//send in 1

var_dump($gen->next());//null next不会返回数据
var_dump($gen->current());//send out 2

var_dump($gen->send('send in 2'));
$gen->next();
var_dump($gen->current());//send out 2Copy

class arrayLikeObj implements ArrayAccess {
  private $container = array();
  public function __construct($arr) {
    $this->container = $arr;
  }
  public function offsetSet($offset, $value) {
    if (is_null($offset)) {
        $this->container[] = $value;
    } else {
        $this->container[$offset] = $value;
    }
  }
  public function offsetExists($offset) {
    return isset($this->container[$offset]);
  }
  public function offsetUnset($offset) {
    unset($this->container[$offset]);
  }
  public function offsetGet($offset) {
    return isset($this->container[$offset]) ? $this->container[$offset] : null;
  }
}

$obj = new arrayLikeObj(array(
  "one"   => 1,
  "two"   => 2,
  "three" => 3,
));

var_dump($obj[1]);Copy

/* Imagine this is memory map
  ______________________________
 |pointer | value | variable                |
  --------------------------------
 |   1     |  NULL  |         ---           |
 |   2     |  NULL  |         ---           |
 |   3     |  NULL  |         ---           |
 |   4     |  NULL  |         ---           |
 |   5     |  NULL  |         ---           |
 ------------------------------------
 Create some variables   */
$a=10;
$b=20;
$c=array ('one'=>array (1, 2, 3));
/* Look at memory
  _______________________________
 |pointer | value |       variable's        |
  -----------------------------------
 |   1     |  10      |      $a             |
 |   2     |  20      |      $b             |
 |   3     |  1       |      $c['one'][0]   |
 |   4     |  2       |      $c['one'][1]   |
 |   5     |  3       |      $c['one'][2]   |
 ------------------------------------
 do  */
$a=&$c['one'][2];
/* Look at memory
  _______________________________
 |pointer | value |       variable's        |
  -----------------------------------
 |   1     |  NULL    |      ---            |  //value of  $a is destroyed and pointer is free
 |   2     |  20      |      $b             |
 |   3     |  1       |      $c['one'][0]   |
 |   4     |  2       |      $c['one'][1]   |
 |   5     |  3       |  $c['one'][2]  ,$a  | // $a is now here
 ------------------------------------
 do  */
$b=&$a;  // or  $b=&$c['one'][2]; result is same as both "$c['one'][2]" and "$a" is at same pointer.
 /* Look at memory
  _________________________________
 |pointer | value |       variable's            |
  --------------------------------------
 |   1     |  NULL    |       ---               |  
 |   2     |  NULL    |       ---               |  //value of  $b is destroyed and pointer is free
 |   3     |  1       |      $c['one'][0]       |
 |   4     |  2       |      $c['one'][1]       |
 |   5     |  3       |$c['one'][2]  ,$a , $b   |  // $b is now here
 ---------------------------------------
 next do */
unset($c['one'][2]);
/* Look at memory
  _________________________________
 |pointer | value |       variable's            |
  --------------------------------------
 |   1     |  NULL    |      ---                |  
 |   2     |  NULL    |      ---                |  
 |   3     |  1       |      $c['one'][0]       |
 |   4     |  2       |      $c['one'][1]       |
 |   5     |  3       |      $a , $b            | // $c['one'][2]  is  destroyed not in memory, not in array
 ---------------------------------------
 next do   */
$c['one'][2]=500;    //now it is in array
 /* Look at memory
  _________________________________
 |pointer | value |       variable's            |
  --------------------------------------
 |   1     |  500     |      $c['one'][2]       |  //created it lands on any(next) free pointer in memory
 |   2     |  NULL    |       ---               |  
 |   3     |  1       |      $c['one'][0]       |
 |   4     |  2       |      $c['one'][1]       |
 |   5     |  3       |      $a , $b            | //this pointer is in use
 ---------------------------------------
 lets tray to return $c['one'][2] at old pointer an remove reference $a,$b.  */
$c['one'][2]=&$a;
 unset($a);
 unset($b);   
/* look at memory
  _________________________________
 |pointer | value |       variable's           |
  --------------------------------------
 |   1     |  NULL    |       ---               |  
 |   2     |  NULL    |       ---               |  
 |   3     |  1       |      $c['one'][0]       |
 |   4     |  2       |      $c['one'][1]       |
 |   5     |  3       |      $c['one'][2]       | //$c['one'][2] is returned, $a,$b is destroyed
 --------------------------------------- ?>
 I hope this helps. Copy