\u9519\u8bef1\uff1aforeach\u5faa\u73af\u540e\u7559\u4e0b\u60ac\u6302\u6307\u9488<\/p>\n
\u5728foreach\u5faa\u73af\u4e2d\uff0c\u5982\u679c\u6211\u4eec\u9700\u8981\u66f4\u6539\u8fed\u4ee3\u7684\u5143\u7d20\u6216\u662f\u4e3a\u4e86\u63d0\u9ad8\u6548\u7387\uff0c\u8fd0\u7528\u5f15\u7528\u662f\u4e00\u4e2a\u597d\u529e\u6cd5\uff1a<\/p>\n
$arr = array(1, 2, 3, 4);<\/p>\n
foreach ($arr as &$value) {<\/p>\n
$value = $value * 2;<\/p>\n
}<\/p>\n
\/\/ $arr is now array(2, 4, 6, 8)<\/p><\/blockquote>\n
\u8fd9\u91cc\u6709\u4e2a\u95ee\u9898\u5f88\u591a\u4eba\u4f1a\u8ff7\u7cca\u3002\u5faa\u73af\u7ed3\u675f\u540e\uff0c$value\u5e76\u672a\u9500\u6bc1\uff0c$value\u5176\u5b9e\u662f\u6570\u7ec4\u4e2d\u6700\u540e\u4e00\u4e2a\u5143\u7d20\u7684\u5f15\u7528\uff0c\u8fd9\u6837\u5728\u540e\u7eed\u5bf9$value\u7684\u4f7f\u7528\u4e2d\uff0c\u5982\u679c\u4e0d\u77e5\u9053\u8fd9\u4e00\u70b9\uff0c\u4f1a\u5f15\u53d1\u4e00\u4e9b\u83ab\u540d\u5947\u5999\u7684\u9519\u8bef:)\u770b\u770b\u4e0b\u9762\u8fd9\u6bb5\u4ee3\u7801\uff1a<\/p>\n
$array = [1, 2, 3];<\/p>\n
echo implode(‘,’, $array), “\\n”;<\/p>\n
foreach ($array as &$value) {} \/\/ by reference<\/p>\n
echo implode(‘,’, $array), “\\n”;<\/p>\n
foreach ($array as $value) {} \/\/ by value (i.e., copy)<\/p>\n
echo implode(‘,’, $array), “\\n”;<\/p><\/blockquote>\n
\u4e0a\u9762\u4ee3\u7801\u7684\u8fd0\u884c\u7ed3\u679c\u5982\u4e0b\uff1a<\/p>\n
1,2,3<\/p>\n
1,2,3<\/p>\n
1,2,2<\/p>\n
\u4f60\u731c\u5bf9\u4e86\u5417\uff1f\u4e3a\u4ec0\u4e48\u662f\u8fd9\u4e2a\u7ed3\u679c\u5462\uff1f<\/p>\n
\u6211\u4eec\u6765\u5206\u6790\u4e0b\u3002\u7b2c\u4e00\u4e2a\u5faa\u73af\u8fc7\u540e\uff0c$value\u662f\u6570\u7ec4\u4e2d\u6700\u540e\u4e00\u4e2a\u5143\u7d20\u7684\u5f15\u7528\u3002\u7b2c\u4e8c\u4e2a\u5faa\u73af\u5f00\u59cb\uff1a<\/p>\n
\u7b2c\u4e00\u6b65\uff1a\u590d\u5236$arr[0]\u5230$value\uff08\u6ce8\u610f\u6b64\u65f6$value\u662f$arr[2]\u7684\u5f15\u7528\uff09\uff0c\u8fd9\u65f6\u6570\u7ec4\u53d8\u6210[1,2,1]<\/p>\n
\u7b2c\u4e8c\u6b65\uff1a\u590d\u5236$arr[1]\u5230$value\uff0c\u8fd9\u65f6\u6570\u7ec4\u53d8\u6210[1,2,2]<\/p>\n
\u7b2c\u4e09\u6b65\uff1a\u590d\u5236$arr[2]\u5230$value\uff0c\u8fd9\u65f6\u6570\u7ec4\u53d8\u6210[1,2,2]<\/p>\n
\u7efc\u4e0a\uff0c\u6700\u7ec8\u7ed3\u679c\u5c31\u662f1,2,2<\/p>\n
\u907f\u514d\u8fd9\u79cd\u9519\u8bef\u6700\u597d\u7684\u529e\u6cd5\u5c31\u662f\u5728\u5faa\u73af\u540e\u7acb\u5373\u7528unset\u51fd\u6570\u9500\u6bc1\u53d8\u91cf\uff1a<\/p>\n
$arr = array(1, 2, 3, 4);<\/p>\n
foreach ($arr as &$value) {<\/p>\n
$value = $value * 2;<\/p>\n
}<\/p>\n
unset($value); \/\/ $value no longer references $arr[3]<\/p><\/blockquote>\n
\u9519\u8bef2\uff1a\u5bf9isset()\u51fd\u6570\u884c\u4e3a\u7684\u9519\u8bef\u7406\u89e3<\/p>\n
\u5bf9\u4e8eisset()\u51fd\u6570\uff0c\u53d8\u91cf\u4e0d\u5b58\u5728\u65f6\u4f1a\u8fd4\u56defalse\uff0c\u53d8\u91cf\u503c\u4e3anull\u65f6\u4e5f\u4f1a\u8fd4\u56defalse\u3002\u8fd9\u79cd\u884c\u4e3a\u5f88\u5bb9\u6613\u628a\u4eba\u5f04\u8ff7\u7cca\u3002\u3002\u3002\u770b\u4e0b\u9762\u7684\u4ee3\u7801\uff1a<\/p>\n
$data = fetchRecordFromStorage($storage, $identifier);<\/p>\n
if (!isset($data[‘keyShouldBeSet’]) {<\/p>\n
\/\/ do something here if ‘keyShouldBeSet’ is not set<\/p>\n
}<\/p><\/blockquote>\n
\u5199\u8fd9\u6bb5\u4ee3\u7801\u7684\u4eba\u672c\u610f\u53ef\u80fd\u662f\u5982\u679c$data[\u2018keyShouldBeSet\u2019]\u672a\u8bbe\u7f6e\uff0c\u5219\u6267\u884c\u5bf9\u5e94\u903b\u8f91\u3002\u4f46\u95ee\u9898\u5728\u4e8e\u5373\u4f7f$data[\u2018keyShouldBeSet\u2019]\u5df2\u8bbe\u7f6e\uff0c\u4f46\u8bbe\u7f6e\u7684\u503c\u4e3anull\uff0c\u8fd8\u662f\u4f1a\u6267\u884c\u5bf9\u5e94\u7684\u903b\u8f91\uff0c\u8fd9\u5c31\u4e0d\u7b26\u5408\u4ee3\u7801\u7684\u672c\u610f\u4e86\u3002<\/p>\n
\u4e0b\u9762\u662f\u53e6\u5916\u4e00\u4e2a\u4f8b\u5b50\uff1a<\/p>\n
if ($_POST[‘active’]) {<\/p>\n
$postData = extractSomething($_POST);<\/p>\n
}<\/p>\n
\/\/ …<\/p>\n
if (!isset($postData)) {<\/p>\n
echo ‘post not active’;<\/p>\n
}<\/p><\/blockquote>\n
\u4e0a \u9762\u7684\u4ee3\u7801\u5047\u8bbe$_POST[\u2018active\u2019]\u4e3a\u771f\uff0c\u90a3\u4e48$postData\u5e94\u8be5\u88ab\u8bbe\u7f6e\uff0c\u56e0\u6b64isset($postData)\u4f1a\u8fd4\u56detrue\u3002\u53cd\u4e4b\uff0c\u4e0a \u9762\u4ee3\u7801\u5047\u8bbeisset($postData)\u8fd4\u56defalse\u7684\u552f\u4e00\u9014\u5f84\u5c31\u662f$_POST[\u2018active\u2019]\u4e5f\u8fd4\u56defalse\u3002<\/p>\n
\u771f\u662f\u8fd9\u6837\u5417\uff1f\u5f53\u7136\u4e0d\u662f\uff01<\/p>\n
\u5373\u4f7f$_POST[\u2018active\u2019]\u8fd4\u56detrue\uff0c$postData\u4e5f\u6709\u53ef\u80fd\u88ab\u8bbe\u7f6e\u4e3anull\uff0c\u8fd9\u65f6isset($postData)\u5c31\u4f1a\u8fd4\u56defalse\u3002\u8fd9\u5c31\u4e0d\u7b26\u5408\u4ee3\u7801\u7684\u672c\u610f\u4e86\u3002<\/p>\n
\u5982\u679c\u4e0a\u9762\u4ee3\u7801\u7684\u672c\u610f\u4ec5\u662f\u68c0\u6d4b$_POST[\u2018active\u2019]\u662f\u5426\u4e3a\u771f\uff0c\u4e0b\u9762\u8fd9\u6837\u5b9e\u73b0\u4f1a\u66f4\u597d\uff1a<\/p>\n
if ($_POST[‘active’]) {<\/p>\n
$postData = extractSomething($_POST);<\/p>\n
}<\/p>\n
\/\/ …<\/p>\n
if ($_POST[‘active’]) {<\/p>\n
echo ‘post not active’;<\/p>\n
}<\/p><\/blockquote>\n
\u5224\u65ad\u4e00\u4e2a\u53d8\u91cf\u662f\u5426\u771f\u6b63\u88ab\u8bbe\u7f6e\uff08\u533a\u5206\u672a\u8bbe\u7f6e\u548c\u8bbe\u7f6e\u503c\u4e3anull\uff09\uff0carray_key_exists()\u51fd\u6570\u6216\u8bb8\u66f4\u597d\u3002\u91cd\u6784\u4e0a\u9762\u7684\u7b2c\u4e00\u4e2a\u4f8b\u5b50\uff0c\u5982\u4e0b\uff1a<\/p>\n
$data = fetchRecordFromStorage($storage, $identifier);<\/p>\n
if (! array_key_exists(‘keyShouldBeSet’, $data)) {<\/p>\n
\/\/ do this if ‘keyShouldBeSet’ isn’t set<\/p>\n
}<\/p><\/blockquote>\n
\u53e6\u5916\uff0c\u7ed3\u5408get_defined_vars()\u51fd\u6570\uff0c\u6211\u4eec\u53ef\u4ee5\u66f4\u52a0\u53ef\u9760\u7684\u68c0\u6d4b\u53d8\u91cf\u5728\u5f53\u524d\u4f5c\u7528\u57df\u5185\u662f\u5426\u88ab\u8bbe\u7f6e\uff1a<\/p>\n
if (array_key_exists(‘varShouldBeSet’, get_defined_vars())) {<\/p>\n
\/\/ variable $varShouldBeSet exists in current scope<\/p>\n
}<\/p><\/blockquote>\n
\u9519\u8bef3\uff1a\u6df7\u6dc6\u8fd4\u56de\u503c\u548c\u8fd4\u56de\u5f15\u7528<\/p>\n
\u8003\u8651\u4e0b\u9762\u7684\u4ee3\u7801\uff1a<\/p>\n
class Config<\/p>\n
{<\/p>\n
private $values = [];<\/p>\n
public function getValues() {<\/p>\n
return $this->values;<\/p>\n
}<\/p>\n
}<\/p>\n
$config = new Config();<\/p>\n
$config->getValues()[‘test’] = ‘test’;<\/p>\n
echo $config->getValues()[‘test’];<\/p><\/blockquote>\n
\u8fd0\u884c\u4e0a\u9762\u7684\u4ee3\u7801\uff0c\u5c06\u4f1a\u8f93\u51fa\u4e0b\u9762\u7684\u5185\u5bb9\uff1a<\/p>\n
PHP Notice: Undefined index: test in \/path\/to\/my\/script.php on line 21<\/p>\n
\u95ee\u9898\u51fa\u5728\u54ea\u5462\uff1f\u95ee\u9898\u5c31\u5728\u4e8e\u4e0a\u9762\u7684\u4ee3\u7801\u6df7\u6dc6\u4e86\u8fd4\u56de\u503c\u548c\u8fd4\u56de\u5f15\u7528\u3002\u5728PHP\u4e2d\uff0c\u9664\u975e\u4f60\u663e\u793a\u7684\u6307\u5b9a\u8fd4\u56de\u5f15\u7528\uff0c\u5426\u5219\u5bf9\u4e8e\u6570\u7ec4PHP\u662f\u503c\u8fd4\u56de\uff0c\u4e5f\u5c31\u662f\u6570\u7ec4\u7684\u62f7\u8d1d\u3002\u56e0\u6b64\u4e0a\u9762\u4ee3\u7801\u5bf9\u8fd4\u56de\u6570\u7ec4\u8d4b\u503c\uff0c\u5b9e\u9645\u662f\u5bf9\u62f7\u8d1d\u6570\u7ec4\u8fdb\u884c\u8d4b\u503c\uff0c\u975e\u539f\u6570\u7ec4\u8d4b\u503c\u3002<\/p>\n
\/\/ getValues() returns a COPY of the $values array, so this adds a ‘test’ element<\/p>\n
\/\/ to a COPY of the $values array, but not to the $values array itself.<\/p>\n
$config->getValues()[‘test’] = ‘test’;<\/p>\n
\/\/ getValues() again returns ANOTHER COPY of the $values array, and THIS copy doesn’t<\/p>\n
\/\/ contain a ‘test’ element (which is why we get the “undefined index” message).<\/p>\n
echo $config->getValues()[‘test’];<\/p><\/blockquote>\n
\u4e0b\u9762\u662f\u4e00\u79cd\u53ef\u80fd\u7684\u89e3\u51b3\u529e\u6cd5\uff0c\u8f93\u51fa\u62f7\u8d1d\u7684\u6570\u7ec4\uff0c\u800c\u4e0d\u662f\u539f\u6570\u7ec4\uff1a<\/p>\n
$vals = $config->getValues();<\/p>\n
$vals[‘test’] = ‘test’;<\/p>\n
echo $vals[‘test’];<\/p><\/blockquote>\n
\u5982\u679c\u4f60\u5c31\u662f\u60f3\u8981\u6539\u53d8\u539f\u6570\u7ec4\uff0c\u4e5f\u5c31\u662f\u8981\u53cd\u56de\u6570\u7ec4\u5f15\u7528\uff0c\u90a3\u5e94\u8be5\u5982\u4f55\u5904\u7406\u5462\uff1f\u529e\u6cd5\u5c31\u662f\u663e\u793a\u6307\u5b9a\u8fd4\u56de\u5f15\u7528\u5373\u53ef\uff1a<\/p>\n
class Config<\/p>\n
{<\/p>\n
private $values = [];<\/p>\n
\/\/ return a REFERENCE to the actual $values array<\/p>\n
public function &getValues() {<\/p>\n
return $this->values;<\/p>\n
}<\/p>\n
}<\/p>\n
$config = new Config();<\/p>\n
$config->getValues()[‘test’] = ‘test’;<\/p>\n
echo $config->getValues()[‘test’];<\/p><\/blockquote>\n
\u7ecf\u8fc7\u6539\u9020\u540e\uff0c\u4e0a\u9762\u4ee3\u7801\u5c06\u4f1a\u50cf\u4f60\u671f\u671b\u90a3\u6837\u4f1a\u8f93\u51fatest\u3002<\/p>\n
\u6211\u4eec\u518d\u6765\u770b\u4e00\u4e2a\u4f8b\u5b50\u4f1a\u8ba9\u4f60\u66f4\u8ff7\u7cca\u7684\u4f8b\u5b50\uff1a<\/p>\n
class Config<\/p>\n
{<\/p>\n
private $values;<\/p>\n
\/\/ using ArrayObject rather than array<\/p>\n
public function __construct() {<\/p>\n
$this->values = new ArrayObject();<\/p>\n
}<\/p>\n
public function getValues() {<\/p>\n
return $this->values;<\/p>\n
}<\/p>\n
}<\/p>\n
$config = new Config();<\/p>\n
$config->getValues()[‘test’] = ‘test’;<\/p>\n
echo $config->getValues()[‘test’];<\/p><\/blockquote>\n
\u5982\u679c\u4f60\u60f3\u7684\u662f\u4f1a\u548c\u4e0a\u9762\u4e00\u6837\u8f93\u51fa\u201c Undefined index\u201d\u9519\u8bef\uff0c\u90a3\u4f60\u5c31\u9519\u4e86\u3002\u4ee3\u7801\u4f1a\u6b63\u5e38\u8f93\u51fa\u201ctest\u201d\u3002\u539f\u56e0\u5728\u4e8ePHP\u5bf9\u4e8e\u5bf9\u8c61\u9ed8\u8ba4\u5c31\u662f\u6309\u5f15\u7528\u8fd4\u56de\u7684\uff0c\u800c\u4e0d\u662f\u6309\u503c\u8fd4\u56de\u3002<\/p>\n
\u7efc\u4e0a\u6240\u8ff0\uff0c\u6211\u4eec\u5728\u4f7f\u7528\u51fd\u6570\u8fd4\u56de\u503c\u65f6\uff0c\u8981\u5f04\u6e05\u695a\u662f\u503c\u8fd4\u56de\u8fd8\u662f\u5f15\u7528\u8fd4\u56de\u3002PHP\u4e2d\u5bf9\u4e8e\u5bf9\u8c61\uff0c\u9ed8\u8ba4\u662f\u5f15\u7528\u8fd4\u56de\uff0c\u6570\u7ec4\u548c\u5185\u7f6e\u57fa\u672c\u7c7b\u578b\u9ed8\u8ba4\u5747\u6309\u503c\u8fd4\u56de\u3002\u8fd9\u4e2a\u8981\u4e0e\u5176\u5b83\u8bed\u8a00\u533a\u522b\u5f00\u6765\uff08\u5f88\u591a\u8bed\u8a00\u5bf9\u4e8e\u6570\u7ec4\u662f\u5f15\u7528\u4f20\u9012\uff09\u3002<\/p>\n
\u50cf\u5176\u5b83\u8bed\u8a00\uff0c\u6bd4\u5982java\u6216C#\uff0c\u5229\u7528getter\u6216setter\u6765\u8bbf\u95ee\u6216\u8bbe\u7f6e\u7c7b\u5c5e\u6027\u662f\u4e00\u79cd\u66f4\u597d\u7684\u65b9\u6848\uff0c\u5f53\u7136PHP\u9ed8\u8ba4\u4e0d\u652f\u6301\uff0c\u9700\u8981\u81ea\u5df1\u5b9e\u73b0\uff1a<\/p>\n
class Config<\/p>\n
{<\/p>\n
private $values = [];<\/p>\n
public function setValue($key, $value) {<\/p>\n
$this->values[$key] = $value;<\/p>\n
}<\/p>\n
public function getValue($key) {<\/p>\n
return $this->values[$key];<\/p>\n
}<\/p>\n
}<\/p>\n
$config = new Config();<\/p>\n
$config->setValue(‘testKey’, ‘testValue’);<\/p>\n
echo $config->getValue(‘testKey’); \/\/ echos ‘testValue’<\/p><\/blockquote>\n
\u4e0a\u9762\u7684\u4ee3\u7801\u7ed9\u8c03\u7528\u8005\u53ef\u4ee5\u8bbf\u95ee\u6216\u8bbe\u7f6e\u6570\u7ec4\u4e2d\u7684\u4efb\u610f\u503c\u800c\u4e0d\u7528\u7ed9\u4e0e\u6570\u7ec4public\u8bbf\u95ee\u6743\u9650\u3002\u611f\u89c9\u600e\u4e48\u6837:)<\/p>\n
\u9519\u8bef4\uff1a\u5728\u5faa\u73af\u4e2d\u6267\u884csql\u67e5\u8be2<\/p>\n
\u5728PHP\u7f16\u7a0b\u4e2d\u53d1\u73b0\u7c7b\u4f3c\u4e0b\u9762\u7684\u4ee3\u7801\u5e76\u4e0d\u5c11\u89c1\uff1a<\/p>\n
$models = [];<\/p>\n
foreach ($inputValues as $inputValue) {<\/p>\n
$models[] = $valueRepository->findByValue($inputValue);<\/p>\n
}<\/p><\/blockquote>\n
\u5f53\u7136\u4e0a\u9762\u7684\u4ee3\u7801\u662f\u6ca1\u6709\u4ec0\u4e48\u9519\u8bef\u7684\u3002\u95ee\u9898\u5728\u4e8e\u6211\u4eec\u5728\u8fed\u4ee3\u8fc7\u7a0b\u4e2d$valueRepository->findByValue()\u53ef\u80fd\u6bcf\u6b21\u90fd\u6267\u884c\u4e86sql\u67e5\u8be2\uff1a<\/p>\n
$result = $connection->query(“SELECT `x`,`y` FROM `values` WHERE `value`=” . $inputValue);<\/p><\/blockquote>\n
\u5982\u679c\u8fed\u4ee3\u4e8610000\u6b21\uff0c\u90a3\u4e48\u4f60\u5c31\u5206\u522b\u6267\u884c\u4e8610000\u6b21sql\u67e5\u8be2\u3002\u5982\u679c\u8fd9\u6837\u7684\u811a\u672c\u5728\u591a\u7ebf\u7a0b\u7a0b\u5e8f\u4e2d\u88ab\u8c03\u7528\uff0c\u90a3\u5f88\u53ef\u80fd\u4f60\u7684\u7cfb\u7edf\u5c31\u6302\u4e86\u3002\u3002\u3002<\/p>\n
\u5728\u7f16\u5199\u4ee3\u7801\u8fc7\u7a0b\u4e2d\uff0c\u4f60\u5e94\u8be5\u8981\u6e05\u695a\u4ec0\u4e48\u65f6\u5019\u5e94\u8be5\u6267\u884csql\u67e5\u8be2\uff0c\u5c3d\u53ef\u80fd\u4e00\u6b21sql\u67e5\u8be2\u53d6\u51fa\u6240\u6709\u6570\u636e\u3002<\/p>\n
\u6709\u4e00\u79cd\u4e1a\u52a1\u573a\u666f\uff0c\u4f60\u5f88\u53ef\u80fd\u4f1a\u72af\u4e0a\u8ff0\u9519\u8bef\u3002\u5047\u8bbe\u4e00\u4e2a\u8868\u5355\u63d0\u4ea4\u4e86\u4e00\u7cfb\u5217\u503c\uff08\u5047\u8bbe\u4e3aIDs\uff09\uff0c\u7136\u540e\u4e3a\u4e86\u53d6\u51fa\u6240\u6709ID\u5bf9\u5e94\u7684\u6570\u636e\uff0c\u4ee3\u7801\u5c06\u904d\u5386IDs\uff0c\u5206\u522b\u5bf9\u6bcf\u4e2aID\u6267\u884csql\u67e5\u8be2\uff0c\u4ee3\u7801\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n
$data = [];<\/p>\n
foreach ($ids as $id) {<\/p>\n
$result = $connection->query(“SELECT `x`, `y` FROM `values` WHERE `id` = ” . $id);<\/p>\n
$data[] = $result->fetch_row();<\/p>\n
}<\/p><\/blockquote>\n
\u4f46\u540c\u6837\u7684\u76ee\u7684\u53ef\u4ee5\u5728\u4e00\u4e2asql\u4e2d\u66f4\u52a0\u9ad8\u6548\u7684\u5b8c\u6210\uff0c\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n
$data = [];<\/p>\n
if (count($ids)) {<\/p>\n
$result = $connection->query(“SELECT `x`, `y` FROM `values` WHERE `id` IN (” . implode(‘,’, $ids));<\/p>\n
while ($row = $result->fetch_row()) {<\/p>\n
$data[] = $row;<\/p>\n
}<\/p>\n
}<\/p><\/blockquote>\n
\u9519\u8bef5\uff1a\u5185\u5b58\u4f7f\u7528\u4f4e\u6548\u548c\u9519\u89c9<\/p>\n
\u4e00\u6b21sql\u67e5\u8be2\u83b7\u53d6\u591a\u6761\u8bb0\u5f55\u6bd4\u6bcf\u6b21\u67e5\u8be2\u83b7\u53d6\u4e00\u6761\u8bb0\u5f55\u6548\u7387\u80af\u5b9a\u8981\u9ad8\uff0c\u4f46\u5982\u679c\u4f60\u4f7f\u7528\u7684\u662fphp\u4e2d\u7684mysql\u6269\u5c55\uff0c\u90a3\u4e48\u4e00\u6b21\u83b7\u53d6\u591a\u6761\u8bb0\u5f55\u5c31\u5f88\u53ef\u80fd\u4f1a\u5bfc\u81f4\u5185\u5b58\u6ea2\u51fa\u3002<\/p>\n
\u6211\u4eec\u53ef\u4ee5\u5199\u4ee3\u7801\u6765\u5b9e\u9a8c\u4e0b\uff08\u6d4b\u8bd5\u73af\u5883\uff1a 512MB RAM\u3001MySQL\u3001php-cli\uff09\uff1a<\/p>\n
\/\/ connect to mysql<\/p>\n
$connection = new mysqli(‘localhost’, ‘username’, ‘password’, ‘database’);<\/p>\n
\/\/ create table of 400 columns<\/p>\n
$query = ‘CREATE TABLE `test`(`id` INT NOT NULL PRIMARY KEY AUTO_INCREMENT’;<\/p>\n
for ($col = 0; $col < 400 col span><\/p>\n
$query .= “, `col$col` CHAR(10) NOT NULL”;<\/p>\n
}<\/p>\n
$query .= ‘);’;<\/p>\n
$connection->query($query);<\/p>\n
\/\/ write 2 million rows<\/p>\n
for ($row = 0; $row < 2000000 row span><\/p>\n
$query = “INSERT INTO `test` VALUES ($row”;<\/p>\n
for ($col = 0; $col < 400 col span><\/p>\n
$query .= ‘, ‘ . mt_rand(1000000000, 9999999999);<\/p>\n
}<\/p>\n
$query .= ‘)’;<\/p>\n
$connection->query($query);<\/p>\n
}<\/p><\/blockquote>\n
\u73b0\u5728\u6765\u770b\u770b\u8d44\u6e90\u6d88\u8017\uff1a<\/p>\n
\/\/ connect to mysql<\/p>\n
$connection = new mysqli(‘localhost’, ‘username’, ‘password’, ‘database’);<\/p>\n
echo “Before: ” . memory_get_peak_usage() . “\\n”;<\/p>\n
$res = $connection->query(‘SELECT `x`,`y` FROM `test` LIMIT 1’);<\/p>\n
echo “Limit 1: ” . memory_get_peak_usage() . “\\n”;<\/p>\n
$res = $connection->query(‘SELECT `x`,`y` FROM `test` LIMIT 10000’);<\/p>\n
echo “Limit 10000: ” . memory_get_peak_usage() . “\\n”;<\/p><\/blockquote>\n
\u8f93\u51fa\u7ed3\u679c\u5982\u4e0b\uff1a<\/p>\n
Before: 224704<\/p>\n
Limit 1: 224704<\/p>\n
Limit 10000: 224704<\/p>\n
\u6839\u636e\u5185\u5b58\u4f7f\u7528\u91cf\u6765\u770b\uff0c\u8c8c\u4f3c\u4e00\u5207\u6b63\u5e38\u3002\u4e3a\u4e86\u66f4\u52a0\u786e\u5b9a\uff0c\u8bd5\u7740\u4e00\u6b21\u83b7\u53d6100000\u6761\u8bb0\u5f55\uff0c\u7ed3\u679c\u7a0b\u5e8f\u5f97\u5230\u5982\u4e0b\u8f93\u51fa\uff1a<\/p>\n
PHP Warning: mysqli::query(): (HY000\/2013):<\/p>\n
Lost connection to MySQL server during query in \/root\/test.php on line 11<\/p><\/blockquote>\n
\u8fd9\u662f\u600e\u4e48\u56de\u4e8b\u5462\uff1f<\/p>\n
\u95ee \u9898\u51fa\u5728php\u7684mysql\u6a21\u5757\u7684\u5de5\u4f5c\u65b9\u5f0f\uff0cmysql\u6a21\u5757\u5b9e\u9645\u4e0a\u5c31\u662flibmysqlclient\u7684\u4e00\u4e2a\u4ee3\u7406\u3002\u5728\u67e5\u8be2\u83b7\u53d6\u591a\u6761\u8bb0\u5f55\u7684\u540c\u65f6\uff0c\u8fd9\u4e9b\u8bb0\u5f55\u4f1a\u76f4\u63a5 \u4fdd\u5b58\u5728\u5185\u5b58\u4e2d\u3002\u7531\u4e8e\u8fd9\u5757\u5185\u5b58\u4e0d\u5c5e\u4e8ephp\u7684\u5185\u5b58\u6a21\u5757\u6240\u7ba1\u7406\uff0c\u6240\u4ee5\u6211\u4eec\u8c03\u7528memory_get_peak_usage()\u51fd\u6570\u6240\u83b7\u5f97\u7684\u503c\u5e76\u975e\u771f\u5b9e\u4f7f\u7528\u5185\u5b58 \u503c\uff0c\u4e8e\u662f\u4fbf\u51fa\u73b0\u4e86\u4e0a\u9762\u7684\u95ee\u9898\u3002<\/p>\n
\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528mysqlnd\u6765\u4ee3\u66ffmysql\uff0cmysqlnd\u7f16\u8bd1\u4e3aphp\u81ea\u8eab\u6269\u5c55\uff0c\u5176\u5185\u5b58\u4f7f\u7528\u7531php\u5185\u5b58\u7ba1\u7406\u6a21\u5757\u6240\u63a7\u5236\u3002\u5982\u679c\u6211\u4eec\u7528mysqlnd\u6765\u5b9e\u73b0\u4e0a\u9762\u7684\u4ee3\u7801\uff0c\u5219\u4f1a\u66f4\u52a0\u771f\u5b9e\u7684\u53cd\u5e94\u5185\u5b58\u4f7f\u7528\u60c5\u51b5\uff1a<\/p>\n
Before: 232048<\/p>\n
Limit 1: 324952<\/p>\n
Limit 10000: 32572912<\/p>\n
\u66f4\u52a0\u7cdf\u7cd5\u7684\u662f\uff0c\u6839\u636ephp\u7684\u5b98\u65b9\u6587\u6863\uff0cmysql\u6269\u5c55\u5b58\u50a8\u67e5\u8be2\u6570\u636e\u4f7f\u7528\u7684\u5185\u5b58\u662fmysqlnd\u7684\u4e24\u500d\uff0c\u56e0\u6b64\u539f\u6765\u7684\u4ee3\u7801\u4f7f\u7528\u7684\u5185\u5b58\u662f\u4e0a\u9762\u663e\u793a\u7684\u4e24\u500d\u5de6\u53f3\u3002<\/p>\n
\u4e3a\u4e86\u907f\u514d\u6b64\u7c7b\u95ee\u9898\uff0c\u53ef\u4ee5\u8003\u8651\u5206\u51e0\u6b21\u5b8c\u6210\u67e5\u8be2\uff0c\u51cf\u5c0f\u5355\u6b21\u67e5\u8be2\u6570\u636e\u91cf\uff1a<\/p>\n
$totalNumberToFetch = 10000;<\/p>\n
$portionSize = 100;<\/p>\n
for ($i = 0; $i < ceiltotalNumberToFetch portionSize i span><\/p>\n
$limitFrom = $portionSize * $i;<\/p>\n
$res = $connection->query(<\/p>\n
“SELECT `x`,`y` FROM `test` LIMIT $limitFrom, $portionSize”);<\/p>\n
}<\/p><\/blockquote>\n
\u8054\u7cfb\u4e0a\u9762\u63d0\u5230\u7684\u9519\u8bef4\u53ef\u4ee5\u770b\u51fa\uff0c\u5728\u5b9e\u9645\u7684\u7f16\u7801\u8fc7\u7a0b\u4e2d\uff0c\u8981\u505a\u5230\u4e00\u79cd\u5e73\u8861\uff0c\u624d\u80fd\u65e2\u6ee1\u8db3\u529f\u80fd\u8981\u6c42\uff0c\u53c8\u80fd\u4fdd\u8bc1\u6027\u80fd\u3002<\/p>\n
\u9519\u8bef6\uff1a\u5ffd\u7565Unicode\/UTF-8\u95ee\u9898<\/p>\n
php\u7f16\u7a0b\u4e2d\uff0c\u5728\u5904\u7406\u975eascii\u5b57\u7b26\u65f6\uff0c\u4f1a\u9047\u5230\u4e00\u4e9b\u95ee\u9898\uff0c\u8981\u5f88\u5c0f\u5fc3\u7684\u53bb\u5bf9\u5f85\uff0c\u8981\u4e0d\u7136\u5c31\u4f1a\u9519\u8bef\u904d\u5730\u3002\u4e3e\u4e2a\u7b80\u5355\u7684\u4f8b\u5b50\uff0cstrlen($name)\uff0c\u5982\u679c$name\u5305\u542b\u975eascii\u5b57\u7b26\uff0c\u90a3\u7ed3\u679c\u5c31\u6709\u4e9b\u51fa\u4e4e\u610f\u6599\u3002\u5728\u6b64\u7ed9\u51fa\u4e00\u4e9b\u5efa\u8bae\uff0c\u5c3d\u91cf\u907f\u514d\u6b64\u7c7b\u95ee\u9898\uff1a<\/p>\n
\n
- \u5982\u679c\u4f60\u5bf9unicode\u548cutf-8\u4e0d\u662f\u5f88\u4e86\u89e3\uff0c\u90a3\u4e48\u4f60\u81f3\u5c11\u5e94\u8be5\u4e86\u89e3\u4e00\u4e9b\u57fa\u7840\u3002\u63a8\u8350\u9605\u8bfb\u8fd9\u7bc7\u6587\u7ae0\u3002<\/li>\n
- \u6700\u597d\u4f7f\u7528mb_*\u51fd\u6570\u6765\u5904\u7406\u5b57\u7b26\u4e32\uff0c\u907f\u514d\u4f7f\u7528\u8001\u7684\u5b57\u7b26\u4e32\u5904\u7406\u51fd\u6570\u3002\u8fd9\u91cc\u8981\u786e\u4fddPHP\u7684\u201cmultibyte\u201d\u6269\u5c55\u5df2\u5f00\u542f\u3002<\/li>\n
- \u6570\u636e\u5e93\u548c\u8868\u6700\u597d\u4f7f\u7528unicode\u7f16\u7801\u3002<\/li>\n
- \u77e5\u9053jason_code()\u51fd\u6570\u4f1a\u8f6c\u6362\u975eascii\u5b57\u7b26\uff0c\u4f46serialize()\u51fd\u6570\u4e0d\u4f1a\u3002<\/li>\n
- php\u4ee3\u7801\u6e90\u6587\u4ef6\u6700\u597d\u4f7f\u7528\u4e0d\u542bbom\u7684utf-8\u683c\u5f0f\u3002<\/li>\n<\/ul>\n
\u5728\u6b64\u63a8\u8350\u4e00\u7bc7\u6587\u7ae0\uff0c\u66f4\u8be6\u7ec6\u7684\u4ecb\u7ecd\u4e86\u6b64\u7c7b\u95ee\u9898\uff1a UTF-8 Primer for PHP and MySQL<\/p>\n
\u9519\u8bef7\uff1a\u5047\u5b9a$_POST\u603b\u662f\u5305\u542bPOST\u6570\u636e<\/p>\n
PHP\u4e2d\u7684$_POST\u5e76\u975e\u603b\u662f\u5305\u542b\u8868\u5355POST\u63d0\u4ea4\u8fc7\u6765\u7684\u6570\u636e\u3002\u5047\u8bbe\u6211\u4eec\u901a\u8fc7 jQuery.ajax() \u65b9\u6cd5\u5411\u670d\u52a1\u5668\u53d1\u9001\u4e86POST\u8bf7\u6c42\uff1a<\/p>\n
\/\/ js<\/p>\n
$.ajax({<\/p>\n
url: ‘http:\/\/my.site\/some\/path’,<\/p>\n
method: ‘post’,<\/p>\n
data: JSON.stringify({a: ‘a’, b: ‘b’}),<\/p>\n
contentType: ‘application\/json’<\/p>\n
});<\/p><\/blockquote>\n
\u6ce8\u610f\u4ee3\u7801\u4e2d\u7684 contentType: \u2018application\/json\u2019 \uff0c\u6211\u4eec\u662f\u4ee5json\u6570\u636e\u683c\u5f0f\u6765\u53d1\u9001\u7684\u6570\u636e\u3002\u5728\u670d\u52a1\u7aef\uff0c\u6211\u4eec\u4ec5\u8f93\u51fa$_POST\u6570\u7ec4\uff1a<\/p>\n
\/\/ php<\/p>\n
var_dump($_POST);<\/p><\/blockquote>\n
\u4f60\u4f1a\u5f88\u60ca\u5947\u7684\u53d1\u73b0\uff0c\u7ed3\u679c\u662f\u4e0b\u9762\u6240\u793a\uff1a<\/p>\n
array(0) { }<\/p><\/blockquote>\n
\u4e3a\u4ec0\u4e48\u662f\u8fd9\u6837\u7684\u7ed3\u679c\u5462\uff1f\u6211\u4eec\u7684json\u6570\u636e {a: \u2018a\u2019, b: \u2018b\u2019} \u54ea\u53bb\u4e86\u5462\uff1f<\/p>\n
\u7b54\u6848\u5c31\u662fPHP\u4ec5\u4ec5\u89e3\u6790Content-Type\u4e3a application\/x-www-form-urlencoded \u6216 multipart\/form-data\u7684Http\u8bf7\u6c42\u3002\u4e4b\u6240\u4ee5\u8fd9\u6837\u662f\u56e0\u4e3a\u5386\u53f2\u539f\u56e0\uff0cPHP\u6700\u521d\u5b9e\u73b0$_POST\u65f6\uff0c\u6700\u6d41\u884c\u7684\u5c31\u662f\u4e0a\u9762\u4e24\u79cd\u7c7b\u578b\u3002\u56e0\u6b64\u867d\u8bf4\u73b0\u5728\u6709\u4e9b\u7c7b\u578b\uff08\u6bd4\u5982application\/json\uff09\u5f88\u6d41\u884c\uff0c\u4f46PHP\u4e2d\u8fd8\u662f\u6ca1\u6709\u53bb\u5b9e\u73b0\u81ea\u52a8\u5904\u7406\u3002<\/p>\n
\u56e0\u4e3a$_POST\u662f\u5168\u5c40\u53d8\u91cf\uff0c\u6240\u4ee5\u66f4\u6539$_POST\u4f1a\u5168\u5c40\u6709\u6548\u3002\u56e0\u6b64\u5bf9\u4e8eContent-Type\u4e3a application\/json \u7684\u8bf7\u6c42\uff0c\u6211\u4eec\u9700\u8981\u624b\u5de5\u53bb\u89e3\u6790json\u6570\u636e\uff0c\u7136\u540e\u4fee\u6539$_POST\u53d8\u91cf\u3002<\/p>\n
\/\/ php<\/p>\n
$_POST = json_decode(file_get_contents(‘php:\/\/input’), true);<\/p><\/blockquote>\n
\u6b64\u65f6\uff0c\u6211\u4eec\u518d\u53bb\u8f93\u51fa$_POST\u53d8\u91cf\uff0c\u5219\u4f1a\u5f97\u5230\u6211\u4eec\u671f\u671b\u7684\u8f93\u51fa\uff1a<\/p>\n
array(2) { [“a”]=> string(1) “a” [“b”]=> string(1) “b” }<\/p><\/blockquote>\n
\u9519\u8bef8\uff1a\u8ba4\u4e3aPHP\u652f\u6301\u5b57\u7b26\u6570\u636e\u7c7b\u578b<\/p>\n
\u770b\u770b\u4e0b\u9762\u7684\u4ee3\u7801\uff0c\u731c\u6d4b\u4e0b\u4f1a\u8f93\u51fa\u4ec0\u4e48\uff1a<\/p>\n
for ($c = ‘a’; $c < z c span><\/p>\n
echo $c . “\\n”;<\/p>\n
}<\/p><\/blockquote>\n
\u5982\u679c\u4f60\u7684\u56de\u7b54\u662f\u8f93\u51fa\u2019a\u2019\u5230\u2019z\u2019\uff0c\u90a3\u4e48\u4f60\u4f1a\u60ca\u5947\u7684\u53d1\u73b0\u4f60\u7684\u56de\u7b54\u662f\u9519\u8bef\u7684\u3002<\/p>\n
\u4e0d\u9519\uff0c\u4e0a\u9762\u7684\u4ee3\u7801\u7684\u786e\u4f1a\u8f93\u51fa\u2019a\u2019\u5230\u2019z\u2019\uff0c\u4f46\u9664\u6b64\u4e4b\u5916\uff0c\u8fd8\u4f1a\u8f93\u51fa\u2019aa\u2019\u5230\u2019yz\u2019\u3002\u6211\u4eec\u6765\u5206\u6790\u4e0b\u4e3a\u4ec0\u4e48\u4f1a\u662f\u8fd9\u6837\u7684\u7ed3\u679c\u3002<\/p>\n
\u5728PHP\u4e2d\u4e0d\u5b58\u5728char\u6570\u636e\u7c7b\u578b\uff0c\u53ea\u6709string\u7c7b\u578b\u3002\u660e\u767d\u8fd9\u70b9\uff0c\u90a3\u4e48\u5bf9\u2019z\u2019\u8fdb\u884c\u9012\u589e\u64cd\u4f5c\uff0c\u7ed3\u679c\u5219\u4e3a\u2019aa\u2019\u3002\u5bf9\u4e8e\u5b57\u7b26\u4e32\u6bd4\u8f83\u5927\u5c0f\uff0c\u5b66\u8fc7C\u7684\u5e94\u8be5\u90fd\u77e5\u9053\uff0c\u2019aa\u2019\u662f\u5c0f\u4e8e\u2019z\u2019\u7684\u3002\u8fd9\u4e5f\u5c31\u89e3\u91ca\u4e86\u4e3a\u4f55\u4f1a\u6709\u4e0a\u9762\u7684\u8f93\u51fa\u7ed3\u679c\u3002<\/p>\n
\u5982\u679c\u6211\u4eec\u60f3\u8f93\u51fa\u2019a\u2019\u5230\u2019z\u2019\uff0c\u4e0b\u9762\u7684\u5b9e\u73b0\u662f\u4e00\u79cd\u4e0d\u9519\u7684\u529e\u6cd5\uff1a<\/p>\n
for ($i = ord(‘a’); $i < ordz i span><\/p>\n
echo chr($i) . “\\n”;<\/p>\n
}<\/p><\/blockquote>\n
\u6216\u8005\u8fd9\u6837\u4e5f\u662fOK\u7684\uff1a<\/p>\n
$letters = range(‘a’, ‘z’);<\/p>\n
for ($i = 0; $i < count letters i span><\/p>\n
echo $letters[$i] . “\\n”;<\/p>\n
}<\/p><\/blockquote>\n
\u9519\u8bef9\uff1a\u5ffd\u7565\u7f16\u7801\u6807\u51c6<\/p>\n
\u867d\u8bf4\u5ffd\u7565\u7f16\u7801\u6807\u51c6\u4e0d\u4f1a\u5bfc\u81f4\u9519\u8bef\u6216\u662fbug\uff0c\u4f46\u9075\u5faa\u4e00\u5b9a\u7684\u7f16\u7801\u6807\u51c6\u8fd8\u662f\u5f88\u91cd\u8981\u7684\u3002<\/p>\n
\u6ca1\u6709\u7edf\u4e00\u7684\u7f16\u7801\u6807\u51c6\u4f1a\u4f7f\u4f60\u7684\u9879\u76ee\u51fa\u73b0\u5f88\u591a\u95ee\u9898\u3002\u6700\u660e\u663e\u7684\u5c31\u662f\u4f60\u7684\u9879\u76ee\u4ee3\u7801\u4e0d\u5177\u6709\u4e00\u81f4\u6027\u3002\u66f4\u574f\u7684\u5730\u65b9\u5728\u4e8e\uff0c\u4f60\u7684\u4ee3\u7801\u5c06\u66f4\u52a0\u96be\u4ee5\u8c03\u8bd5\u3001\u6269\u5c55\u548c\u7ef4\u62a4\u3002\u8fd9\u4e5f\u5c31\u610f\u5473\u7740\u4f60\u7684\u56e2\u961f\u6548\u7387\u4f1a\u964d\u4f4e\uff0c\u5305\u62ec\u505a\u4e00\u4e9b\u5f88\u591a\u65e0\u610f\u4e49\u7684\u52b3\u52a8\u3002<\/p>\n
\u5bf9\u4e8ePHP\u5f00\u53d1\u8005\u6765\u8bf4\uff0c\u662f\u6bd4\u8f83\u5e78\u8fd0\u7684\u3002\u56e0\u4e3a\u6709PHP\u7f16\u7801\u6807\u51c6\u63a8\u8350\uff08PSR\uff09\uff0c\u7531\u4e0b\u97625\u4e2a\u90e8\u5206\u7ec4\u6210\uff1a<\/p>\n
\n
- PSR-0\uff1a\u81ea\u52a8\u52a0\u8f7d\u6807\u51c6<\/li>\n
- PSR-1\uff1a\u57fa\u672c\u7f16\u7801\u6807\u51c6<\/li>\n
- PSR-2\uff1a\u7f16\u7801\u98ce\u683c\u6307\u5357<\/li>\n
- PSR-3\uff1a\u65e5\u5fd7\u63a5\u53e3\u6807\u51c6<\/li>\n
- PSR-4\uff1a\u81ea\u52a8\u52a0\u8f7d<\/li>\n<\/ul>\n
PSR\u6700\u521d\u7531PHP\u793e\u533a\u7684\u51e0\u4e2a\u5927\u7684\u56e2\u4f53\u6240\u521b\u5efa\u5e76\u9075\u5faa\u3002Zend, Drupal, Symfony, Joomla\u53ca\u5176\u5b83\u7684\u5e73\u53f0\u90fd\u4e3a\u6b64\u6807\u51c6\u505a\u8fc7\u8d21\u732e\u5e76\u9075\u5faa\u8fd9\u4e2a\u6807\u51c6\u3002\u5373\u4f7f\u662fPEAR\uff0c\u65e9\u4e9b\u5e74\u4e5f\u60f3\u8ba9\u81ea\u5df1\u6210\u4e3a\u4e00\u4e2a\u6807\u51c6\uff0c\u4f46\u73b0\u5728\u4e5f\u52a0\u5165\u4e86PSR\u9635\u8425\u3002<\/p>\n
\u5728 \u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u4f7f\u7528\u4ec0\u4e48\u7f16\u7801\u6807\u51c6\u662f\u65e0\u5173\u7d27\u8981\u7684\uff0c\u53ea\u8981\u4f60\u4f7f\u7528\u4e00\u79cd\u7f16\u7801\u98ce\u683c\u5e76\u4e00\u76f4\u575a\u6301\u4f7f\u7528\u5373\u53ef\u3002\u4f46\u662f\u9075\u5faaPSR\u6807\u51c6\u4e0d\u5931\u4e3a\u4e00\u4e2a\u597d\u529e\u6cd5\uff0c\u9664\u975e\u4f60\u6709\u4ec0\u4e48\u7279\u6b8a\u7684\u539f\u56e0\u8981 \u81ea\u5df1\u5f04\u4e00\u5957\u3002\u73b0\u5728\u8d8a\u6765\u8d8a\u591a\u7684\u9879\u76ee\u90fd\u5f00\u59cb\u4f7f\u7528PSR\uff0c\u5927\u90e8\u5206\u7684PHP\u5f00\u53d1\u8005\u4e5f\u5728\u4f7f\u7528PSR\uff0c\u56e0\u6b64\u4f7f\u7528PSR\u4f1a\u8ba9\u65b0\u52a0\u5165\u4f60\u56e2\u961f\u7684\u6210\u5458\u66f4\u5feb\u7684\u719f\u6089\u9879\u76ee\uff0c\u5199\u4ee3\u7801\u65f6 \u4e5f\u4f1a\u66f4\u52a0\u8212\u9002\u3002<\/p>\n
\u9519\u8bef10\uff1a\u9519\u8bef\u4f7f\u7528empty()\u51fd\u6570<\/p>\n
\u4e00\u4e9bPHP\u5f00\u53d1\u4eba\u5458\u559c\u6b22\u7528empty()\u51fd\u6570\u53bb\u5bf9\u53d8\u91cf\u6216\u8868\u8fbe\u5f0f\u505a\u5e03\u5c14\u5224\u65ad\uff0c\u4f46\u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\u4f1a\u8ba9\u4eba\u5f88\u56f0\u60d1\u3002<\/p>\n
\u9996\u5148\u6211\u4eec\u6765\u770b\u770bPHP\u4e2d\u7684\u6570\u7ec4Array\u548c\u6570\u7ec4\u5bf9\u8c61ArrayObject\u3002\u770b\u4e0a\u53bb\u597d\u50cf\u6ca1\u4ec0\u4e48\u533a\u522b\uff0c\u90fd\u662f\u4e00\u6837\u7684\u3002\u771f\u7684\u8fd9\u6837\u5417\uff1f<\/p>\n
\/\/ PHP 5.0 or later:<\/p>\n
$array = [];<\/p>\n
var_dump(empty($array)); \/\/ outputs bool(true)<\/p>\n
$array = new ArrayObject();<\/p>\n
var_dump(empty($array)); \/\/ outputs bool(false)<\/p>\n
\/\/ why don’t these both produce the same output?<\/p><\/blockquote>\n
\u8ba9\u4e8b\u60c5\u53d8\u5f97\u66f4\u590d\u6742\u4e9b\uff0c\u770b\u770b\u4e0b\u9762\u7684\u4ee3\u7801\uff1a<\/p>\n
\/\/ Prior to PHP 5.0:<\/p>\n
$array = [];<\/p>\n
var_dump(empty($array)); \/\/ outputs bool(false)<\/p>\n
$array = new ArrayObject();<\/p>\n
var_dump(empty($array)); \/\/ outputs bool(false)<\/p><\/blockquote>\n
\u5f88\u4e0d\u5e78\u7684\u662f\uff0c\u4e0a\u9762\u8fd9\u79cd\u65b9\u6cd5\u5f88\u53d7\u6b22\u8fce\u3002\u4f8b\u5982\uff0c\u5728Zend Framework 2\u4e2d\uff0cZend\\Db\\TableGateway \u5728 TableGateway::select() \u7ed3\u679c\u96c6\u4e0a\u8c03\u7528 current() \u65b9\u6cd5\u8fd4\u56de\u6570\u636e\u96c6\u65f6\u5c31\u662f\u8fd9\u4e48\u5e72\u7684\u3002\u5f00\u53d1\u4eba\u5458\u5f88\u5bb9\u6613\u5c31\u4f1a\u8e29\u5230\u8fd9\u4e2a\u5751\u3002<\/p>\n
\u4e3a\u4e86\u907f\u514d\u8fd9\u4e9b\u95ee\u9898\uff0c\u68c0\u67e5\u4e00\u4e2a\u6570\u7ec4\u662f\u5426\u4e3a\u7a7a\u6700\u540e\u7684\u529e\u6cd5\u662f\u7528 count() \u51fd\u6570\uff1a<\/p>\n
\/\/ Note that this work in ALL versions of PHP (both pre and post 5.0):<\/p>\n
$array = [];<\/p>\n
var_dump(count($array)); \/\/ outputs int(0)<\/p>\n
$array = new ArrayObject();<\/p>\n
var_dump(count($array)); \/\/ outputs int(0)<\/p><\/blockquote>\n
\u5728\u8fd9\u987a\u4fbf\u63d0\u4e00\u4e0b\uff0c\u56e0\u4e3aPHP\u4e2d\u4f1a\u5c06\u6570\u503c0\u8ba4\u4e3a\u662f\u5e03\u5c14\u503cfalse\uff0c\u56e0\u6b64 count() \u51fd\u6570\u53ef\u4ee5\u76f4\u63a5\u7528\u5728 if \u6761\u4ef6\u8bed\u53e5\u7684\u6761\u4ef6\u5224\u65ad\u4e2d\u6765\u5224\u65ad\u6570\u7ec4\u662f\u5426\u4e3a\u7a7a\u3002\u53e6\u5916\uff0ccount() \u51fd\u6570\u5bf9\u4e8e\u6570\u7ec4\u6765\u8bf4\u590d\u6742\u5ea6\u4e3aO(1)\uff0c\u56e0\u6b64\u7528 count() \u51fd\u6570\u662f\u4e00\u4e2a\u660e\u667a\u7684\u9009\u62e9\u3002<\/p>\n
\u518d\u6765\u770b\u4e00\u4e2a\u7528 empty() \u51fd\u6570\u5f88\u5371\u9669\u7684\u4f8b\u5b50\u3002\u5f53\u5728\u9b54\u672f\u65b9\u6cd5 __get() \u4e2d\u7ed3\u5408\u4f7f\u7528 empty() \u51fd\u6570\u65f6\uff0c\u4e5f\u662f\u5f88\u5371\u9669\u7684\u3002\u6211\u4eec\u6765\u5b9a\u4e49\u4e24\u4e2a\u7c7b\uff0c\u6bcf\u4e2a\u7c7b\u90fd\u6709\u4e00\u4e2a test \u5c5e\u6027\u3002<\/p>\n
\u9996\u5148\u6211\u4eec\u5b9a\u4e49 Regular \u7c7b\uff0c\u6709\u4e00\u4e2a test \u5c5e\u6027\uff1a<\/p>\n
class Regular<\/p>\n
{<\/p>\n
public $test = ‘value’;<\/p>\n
}<\/p><\/blockquote>\n
\u7136\u540e\u6211\u4eec\u5b9a\u4e49 Magic \u7c7b\uff0c\u5e76\u7528 __get() \u9b54\u672f\u65b9\u6cd5\u6765\u8bbf\u95ee\u5b83\u7684 test \u5c5e\u6027\uff1a<\/p>\n
class Magic<\/p>\n
{<\/p>\n
private $values = [‘test’ => ‘value’];<\/p>\n
public function __get($key)<\/p>\n
{<\/p>\n
if (isset($this->values[$key])) {<\/p>\n
return $this->values[$key];<\/p>\n
}<\/p>\n
}<\/p>\n
}<\/p><\/blockquote>\n
\u597d\u4e86\u3002\u6211\u4eec\u73b0\u5728\u6765\u770b\u770b\u8bbf\u95ee\u5404\u4e2a\u7c7b\u7684 test \u5c5e\u6027\u4f1a\u53d1\u751f\u4ec0\u4e48\uff1a<\/p>\n
$regular = new Regular();<\/p>\n
var_dump($regular->test); \/\/ outputs string(4) “value”<\/p>\n
$magic = new Magic();<\/p>\n
var_dump($magic->test); \/\/ outputs string(4) “value”<\/p><\/blockquote>\n
\u5230\u76ee\u524d\u4e3a\u6b62\uff0c\u90fd\u8fd8\u662f\u6b63\u5e38\u7684\uff0c\u6ca1\u6709\u8ba9\u6211\u4eec\u611f\u5230\u8ff7\u7cca\u3002<\/p>\n
\u4f46\u5728 test \u5c5e\u6027\u4e0a\u4f7f\u7528 empty() \u51fd\u6570\u4f1a\u600e\u4e48\u6837\u5462\uff1f<\/p>\n
var_dump(empty($regular->test)); \/\/ outputs bool(false)<\/p>\n
var_dump(empty($magic->test)); \/\/ outputs bool(true)<\/p><\/blockquote>\n
\u7ed3\u679c\u662f\u4e0d\u662f\u5f88\u610f\u5916\uff1f<\/p>\n
\u5f88\u4e0d\u5e78\u7684\u662f\uff0c\u5982\u679c\u4e00\u4e2a\u7c7b\u4f7f\u7528\u9b54\u6cd5 __get() \u51fd\u6570\u6765\u8bbf\u95ee\u7c7b\u5c5e\u6027\u7684\u503c\uff0c\u6ca1\u6709\u7b80\u5355\u7684\u65b9\u6cd5\u6765\u68c0\u67e5\u5c5e\u6027\u503c\u662f\u5426\u4e3a\u7a7a\u6216\u662f\u4e0d\u5b58\u5728\u3002\u5728\u7c7b\u4f5c\u7528\u57df\u5916\uff0c\u4f60\u53ea\u80fd\u68c0\u67e5\u662f\u5426\u8fd4\u56de null \u503c\uff0c\u4f46\u8fd9\u5e76\u4e0d\u4e00\u5b9a\u610f\u5473\u7740\u6ca1\u6709\u8bbe\u7f6e\u76f8\u5e94\u7684\u952e\uff0c\u56e0\u4e3a\u952e\u503c\u53ef\u4ee5\u88ab\u8bbe\u7f6e\u4e3a null \u3002<\/p>\n
\u76f8\u6bd4\u4e4b\u4e0b\uff0c\u5982\u679c\u6211\u4eec\u8bbf\u95ee Regular \u7c7b\u7684\u4e00\u4e2a\u4e0d\u5b58\u5728\u7684\u5c5e\u6027\uff0c\u5219\u4f1a\u5f97\u5230\u4e00\u4e2a\u7c7b\u4f3c\u4e0b\u9762\u7684Notice\u6d88\u606f\uff1a<\/p>\n
Notice: Undefined property: Regular::$nonExistantTest in \/path\/to\/test.php on line 10<\/p>\n
Call Stack:<\/p>\n
0.0012 234704 1. {main}() \/path\/to\/test.php:0<\/p>\n
\u56e0\u6b64\uff0c\u5bf9\u4e8e empty() \u51fd\u6570\uff0c\u6211\u4eec\u8981\u5c0f\u5fc3\u7684\u4f7f\u7528\uff0c\u8981\u4e0d\u7136\u7684\u8bdd\u5c31\u4f1a\u7ed3\u679c\u51fa\u4e4e\u610f\u6599\uff0c\u751a\u81f3\u6f5c\u5728\u7684\u8bef\u5bfc\u4f60\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u9519\u8bef1\uff1aforeach\u5faa\u73af\u540e\u7559\u4e0b\u60ac\u6302\u6307\u9488 \u5728foreach\u5faa\u73af\u4e2d\uff0c\u5982\u679c\u6211\u4eec\u9700\u8981\u66f4\u6539\u8fed\u4ee3\u7684\u5143\u7d20\u6216\u662f\u4e3a\u4e86\u63d0\u9ad8\u6548\u7387\uff0c … \u7ee7\u7eed\u9605\u8bfb\u201cPHP\u7f16\u7a0b\u4e2d10\u4e2a\u6700\u5e38\u89c1\u7684\u9519\u8bef\u201d<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[3],"tags":[7],"_links":{"self":[{"href":"http:\/\/www.homconnect.cn\/index.php?rest_route=\/wp\/v2\/posts\/91"}],"collection":[{"href":"http:\/\/www.homconnect.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.homconnect.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.homconnect.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.homconnect.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=91"}],"version-history":[{"count":1,"href":"http:\/\/www.homconnect.cn\/index.php?rest_route=\/wp\/v2\/posts\/91\/revisions"}],"predecessor-version":[{"id":92,"href":"http:\/\/www.homconnect.cn\/index.php?rest_route=\/wp\/v2\/posts\/91\/revisions\/92"}],"wp:attachment":[{"href":"http:\/\/www.homconnect.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=91"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.homconnect.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=91"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.homconnect.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=91"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}