![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
PHPzCorrection status：qualified
Teacher's comments：
Collection
Collection
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>计算器</title>
</head>
<body >
<h2>实现一个计算器</h2>
<table>
<form action="" method="post">
<tr>
<td>请输入第一个数 <input type="number" name="num1" required value = "<?=$_POST['num1']?>"/><td>
<td>
<select name="opt">
<option value="+" <?=$_POST["opt"] == "+" ? "selected" : "" ?>>+</option>
<option value="-" <?=$_POST["opt"] == "-" ? "selected" : "" ?>>-</option>
<option value="*" <?=$_POST["opt"] == "*" ? "selected" : "" ?>>*</option>
<option value="/" <?=$_POST["opt"] == "/" ? "selected" : "" ?>>/</option>
<option value="%" <?=$_POST["opt"] == "%" ? "selected" : "" ?>>%</option>
</select>
</td>
<td>请输入第二个数 <input type="number" name="num2" required value = "<?=$_POST['num2']?>"/></td>
<td>
<input type="submit" name="sub" value="计算">
</td>
<tr>
</form>
<?php
if(isset($_POST['sub']))://判断用户是否点击了计算按钮:
if($_POST['opt'] == '/' && $_POST['num2'] == 0 || $_POST['opt'] == '%' && $_POST['num2'] == 0):
echo $mess = "<h3 style='color:red;'>除数不能为0</h3>";
endif;
endif;
?>
<?php
error_reporting(E_ALL & ~E_NOTICE); //屏蔽 NOTICE 的错误
$num1 = isset($_POST['num1']) ? $_POST['num1'] :0; //三元运算符 判断是否获得num1的值 默认为0
$num2 = isset($_POST['num2']) ? $_POST['num2'] :0; //三元运算符 判断是否获得num2的值 默认为0
$opt = isset($_POST['opt']) ? $_POST['opt'] : '+'; //三元运算符 判断是否获得运算符的值 默认为加法
$mess = isset($_POST['mess']) ? $_POST['mess'] : ''; //三元运算符 判断是否获得错误提示
if(!$mess && isset($_POST['sub']) ):
switch($_POST['opt']):
case '+':
$result = (int)$_POST['num1'] + (int)$_POST['num2']; break;
case '-':
$result = (int)$_POST['num1'] - (int)$_POST['num2']; break;
case '*':
$result = (int)$_POST['num1'] * (int)$_POST['num2']; break;
case "/":
$result = (int)$_POST['num1'] / (int)$_POST['num2']; break;
case "%":
$result = (int)$_POST['num1'] % (int)$_POST['num2']; break;
endswitch;
$res = "计算结果: {$_POST['num1']} {$_POST["opt"]} {$_POST['num2']} = {$result}";
echo "<h3 style='color:green;'>{$res}</h3>";
else:
echo $mess;
endif;
?>
</table>
<hr>
<h2>筛选奇数组成新的数组并返回</h2>
<p>99,72,35,18,7,54,39</p>
<?php
$arr = [99,72,35,18,7,54,39];
function odd(array $arr):array //odd是数组
{
$newArr = []; //声明一个新的空数组
for ($i=0; $i < count($arr) ; $i++) {
if($arr[$i] % 2 != 0)//加上！就是奇数，不加是偶数==？？？
{
array_push($newArr,$arr[$i]);
}
}
return $newArr; //返回新数组
}
var_dump(odd($arr)); //打印输出
?>
</body>
</html>