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When the value being judged is a constant (fixed value), the operating efficiency of switch is higher than that of ifelse; (recommended learning: PHP Programming from Beginner to Master)
$status=3; // 变判断的值为常量 switch($status){ case 1: echo '常量值为1'; break; // 跳出循环 case 2: echo '常量值为2'; break; case 3: echo '常量值为3'; break; }
When the judged value is a variable, the operating efficiency of ifelse is higher than that of switch. Ifelse implements the policy of judging to the end and will start judging from the first condition , until the last else, so it is beneficial to learn to use switch;
$a = $_GET['a']; // 通过get传值后接值; 被判断的值 if($a=1){ echo '变量a的值为1'; }elseif($a=2){ echo '变量a的值为2'; }elseif($a=3){ echo '变量a的值为3'; }else{ echo '变量a的值为不知道'; }
PS: ifelse and switch can also be used for single-condition judgment, but ifelse is suitable for multi-condition judgment and switch is not applicable.
$a = $_GET['a']; // 通过get传值后接值; 被判断的值 if(!empty($a) && $a=1){ echo '变量a的值为1'; }elseif(!empty($a) && $a=2){ echo '变量a的值为2'; }elseif(!empty($a) && $a=3){ echo '变量a的值为3'; }else{ echo '变量a的值为不知道'; }
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