PHP Summary (i)

 ' 1 ', ' key ' = ' 2 ', an array of 1=>3 */$arr []= "1"; $arr ["Key"]= "2"; $arr []=3;/** * @2 * isset to determine whether a variable exists, or a value of NULL * The first to assign a value to $name, by $name judge, there will be a warning in the course of the assignment */$name =$_get["name"]; if (Isset ($name)) {echo "true";} if (Isset ($_get["name")) {echo "true";}/** * @3 * = = = operator Compare size and type, = = Compare size * Output ==,null and Fals E is equal in the case of = =, when using = = = Unequal/$BL =null; $bol =false; if ($BL = = $bol) {echo "= =";} if ($bl = = = $bol) {echo "= = =";}/** * @4 * Static member variable must have a $ $ symbol * GetName default to a static member method, the difference $this->name  */class user{public static $var =array (1), public $name, function GetName () {Var_dump (self:: $var); }} user::getname (); /** * @5 * $count have an undefined variable warning, but still output 6,for the variable is not part of a local variable. * Default $count is initialized to 0 */for ($i =0; $i <4; $i + +) {$count + = $i;} echo $count; /** * @6 * Two conditions as long as there is a set, the OR operator displays a record * using field = $condition OR $condition = ' ' means that the $condition exists on the filter, does not exist to ignore the condition * in operator is generally used at the end of SQL, Improve efficiency. */$sql = "SELECT * from Persons WHERE (firstname= ' Thomas ' OR firstname= ' William ') and lastname= ' Carter '";? >

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