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php method to implement a calculator: first create a PHP sample file; then use the if statement to determine whether the post has passed the sub parameter; then use the switch statement to determine whether the two operands are numbers; finally create a simple calculation The HTML code of the server is sufficient.
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<?php
// 判断post是否传过来sub参数,从而判断是提交计算,还是刷新页面
if (isset($_POST['sub'])){
echo "用户点击提交按钮，提交计算请求<br>";
// 下面注释掉的代码并不是错误的，只是区别switch的另外一种方式
// if ($_POST['ysf'] == "+"){
// echo $_POST['num1'] + $_POST['num2'] . "<br>";
// }elseif ($_POST['ysf'] == "-"){
// echo $_POST['num1'] - $_POST['num2'] . "<br>";
// }elseif ($_POST['ysf'] == "*"){
// echo $_POST['num1'] * $_POST['num2'] . "<br>";
// }elseif ($_POST['ysf'] == "/"){
// echo $_POST['num1'] / $_POST['num2'] . "<br>";
// }elseif ($_POST['ysf'] == "%"){
// echo $_POST['num1'] % $_POST['num2'] . "<br>";
// }
// 判断两个运算元是否为数字 如果不是数字 则不进行运算
if (!is_numeric($_POST['num1']) || !is_numeric($_POST['num2'])){
$isDo = false;
echo "其中一个运算元不是数字，不进行运算<br>";
}else{
$isDo = true;
}
// 声明变量 计算结果
$sum = "";
if ($isDo){ // 判断两个运算元是否为数字 如果不是数字 则不进行运算
switch ($_POST['ysf']){
case '+':
$sum = $_POST['num1'] + $_POST['num2'];
break;
case '-':
$sum = $_POST['num1'] - $_POST['num2'];
break;
case '*':
$sum = $_POST['num1'] * $_POST['num2'];
break;
case '/':
$sum = $_POST['num1'] / $_POST['num2'];
break;
case '%':
$sum = $_POST['num1'] % $_POST['num2'];
break;
}
echo $sum."<br>";
}
}else{
echo "用户刷新页面<br>";
//die("不做计算处理<br>");
}
?>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>简易计算器</title>
</head>
<body>
<!--table 表格-->
<!--border=1，表格周围的边框设置为1像素宽-->
<!--width=400，表格宽度为400像素宽-->
<!--align=center，表格水平对齐方式为居中对齐内容-->
<!--caption 定义表格标题-->
<!--<h1> 定义最大的标题。<h6> 定义最小的标题。-->
<!--<tr> 标签定义 HTML 表格中的行。包含一个或多个th或td元素。-->
<!--ysf 运算符的首字母。-->
<!--colspan 规定单元格可横跨的列数。-->
<table border="1" width="400" align="center">
<form action="jsq2.php" method="post">
<caption><h1>简易计算器</h1></caption>
<caption><h4>iwanghang</h4></caption>
<tr>
<!--第一个运算元-->
<!-- <td><input type="text" size="5" name="num1" value=""></td>-->
<td><input type="text" size="5" name="num1" value="<?php
if (isset($_POST['sub'])){echo $_POST['num1'];} ?>"></td>
<!--运算符-->
<td>
<select name="ysf">
<!-- <option value="+"> + </option>-->
<!-- <option value="-"> - </option>-->
<!-- <option value="*"> * </option>-->
<!-- <option value="/"> / </option>-->
<!-- <option value="%"> % </option>-->
<option <?php if (isset($_POST['sub'])){
if ($_POST['ysf']=="+") echo "selected";} ?> value="+"> + </option>
<option <?php if (isset($_POST['sub'])){
if ($_POST['ysf']=="-") echo "selected";} ?> value="-"> - </option>
<option <?php if (isset($_POST['sub'])){
if ($_POST['ysf']=="*") echo "selected";} ?> value="*"> * </option>
<option <?php if (isset($_POST['sub'])){
if ($_POST['ysf']=="/") echo "selected";} ?> value="/"> / </option>
<option <?php if (isset($_POST['sub'])){
if ($_POST['ysf']=="%") echo "selected";} ?> value="%"> % </option>
</select>
</td>
<!--第二个运算元-->
<!-- <td><input type="text" size="5" name="num2" value=""></td>-->
<td><input type="text" size="5" name="num2" value="<?php
if (isset($_POST['sub'])){echo $_POST['num2'];} ?>"></td>
<!--提交-->
<td><input type="submit" name="sub" value="等于"></td>
</tr>
<tr>
<td colspan="4">
<?php
if (isset($_POST['sub'])){
echo "计算结果：{$_POST['num1']}{$_POST['ysf']}{$_POST['num2']} = {$sum}";
}
?>
</td>
</tr>
</form>
</table>
</body>
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