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PHPzCorrection status：qualified
Teacher's comments：
Collection
Collection
+、减 -、乘 \*、除 /、取余 %=、加 +=、减 -=、乘 \*=、除 /=、取余 %=++$a、后递增 $a++、先递减 --$a 、后递减 $a--==、不等于 !=、大于 > 、小于 <、大于等于 >=、小于等于 <= 、恒等于 ===、恒不等于 !==&&、或 ||、非 !、异或 xorPHP 代码部分:
$n1 = (int)isset($_POST["num1"])?$_POST["num1"]:"";$n2 = (int)isset($_POST["num2"])?$_POST["num2"]:"";$opt = isset($_POST["opt"])?$_POST["opt"]:"1";$v = null;if (!empty($_POST)) {switch ($opt) {case '1':$v = $n1 + $n2;break;case '2':$v = $n1 - $n2;break;case '3':$v = $n1 * $n2;break;case '4':$v = $n1 / $n2;break;case '5':$v = $n1 % $n2;break;default:$v = 0;break;}}
HTML 代码部分:
<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>简易计算器</title><style>input,select{max-width:50px; height:20px; line-height:20px;}</style></head><body><h4>简易计算器</h4><form action="calc.php" method="post"><input type="text" name="num1" value="<?=$n1?>"><select name="opt"><option value="1" <?=$opt=="1"?'selected':""?> >+</option><option value="2" <?=$opt=="2"?'selected':""?> >-</option><option value="3" <?=$opt=="3"?'selected':""?> >*</option><option value="4" <?=$opt=="4"?'selected':""?> >/</option><option value="5" <?=$opt=="5"?'selected':""?> >%</option></select><input type="text" name="num2" value="<?=$n2?>"><input type="submit" value="="><input type="text" value="<?=$v?>"></form></body></html>
效果展示: