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PHP self-study no00010 special data type null value

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Release： 2016-07-29 08:51:01

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<!--中间数组和对象在以后第7章和第14章可以学到这里书上略过-->
<!--特殊数据类型包括资源和空值-->
<!--资源通过专门的函数来建立和使用-->
<!--空值null3种情况，没赋任何值，被赋值null，被unset()函数销毁-->
<?php error_reporting(E_ALL ^ E_NOTICE); //忽略错误
	$string1 = null;
	$string3 = "str";
	if(is_null($string1))		//is_null()函数是判断变量是否为空
		echo &#39;$string1 = null&#39;;
	if(is_null($string2))
		echo &#39;$string2 = null&#39;;
	unset($string3);			//销毁$string3变量  没有值了变为null
	if(is_null($string3))
		echo &#39;$string3 = null&#39;;
?>

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PHP self-study no00010 special data type null value

The above has introduced the null value of the special data type no00010 in PHP self-study, including the relevant content. I hope it will be helpful to friends who are interested in PHP tutorials.

Related labels：

echo lt null string

source：php.cn

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