1、效果:
2、知识点:
- 主要使用http的GET方式记录提交表单的数据;
- 同时也使用了PHP的函数来检测数据的变化;
- 也使用了判断语句if和开关语句switch进行切换判断用户的选择。
3、函数:
isset
![image.png](https://cdn.nlark.com/yuque/0/2019/png/113562/1553759129254-b1fd446f-1dd4-4183-b342-52d104e53e56.png#align=left&display=inline&height=454&name=image.png&originHeight=454&originWidth=1069&size=57929&status=done&width=1069)
$_GET
- is_null
4、代码:**
1)HTML + 部分PHP代码
<div class="wrap">
<header>
<p>简易四则运算器</p>
</header>
<div class="main">
<form>
<input type="text" name="num1" id="num" value="<?php if(isset($_GET['num1'])) echo $_GET['num1'] ?>">
<select name="opt" id="opt">
<option value="+">+</option>
<option value="-">-</option>
<option value="*">*</option>
<option value="/">/</option>
</select>
<input type="text" name="num2" id="num" value="<?php if(isset($_GET['num2'])) echo $_GET['num2'] ?>">
<button name="btn">=</button>
</form>
<div class="result">
<?php
if(isset($result)) {
echo $result;
}
?>
</div>
</div>
<footer>
<p>网站开发专业实例</p>
</footer>
</div>
2)CSS
@charset "utf8";
* {
margin: 0;
padding: 0;
}
body {
height: 100%;
min-height: 100%;
position: relative;
}
.wrap {
width: 650px;
padding: 120px 250px;
}
header {
padding: 18px;
height: 68px;
line-height: 68px;
}
header p {
font-size: 28px;
}
.main {
height: 250px;
}
.main #num {
height: 20px;
padding: 4px;
}
.main #opt {
height: 32px;
padding: 6px;
}
button {
height: 32px;
width: 68px;
padding: 6px;
}
footer {
height: 38px;
position: absolute;
bottom: 0;
}
footer p {
line-height: 38px;
}
3)PHP
<?php
$result = "";
if(isset($_GET['btn'])) {
// var_dump($_GET);
// var_dump($_GET['num1'] && !empty($_GET['num1']));
// exit;
if(!isset($_GET['num1']) || is_null($_GET['num1'])) {
$result .= "请填写第一个操作数";
} else if(!isset($_GET['num2']) || is_null($_GET['num2'])) {
$result .= "请填写第二个操作数";
} else {
if(isset($_GET['opt'])) {
switch($_GET['opt']) {
case '+' :
$result = $_GET['num1'] + $_GET['num2'];
break;
case '-' :
$result = $_GET['num1'] - $_GET['num2'];
break;
case '*' :
$result = $_GET['num1'] * $_GET['num2'];
break;
case '/' :
if($_GET['num2'] <> 0) {
$result = $_GET['num1'] / $_GET['num2'];
} else {
$result = "除数不能为零!";
}
break;
}
} else {
$result .= "请选择运算符";
}
}
}
?>