1 <!DOCTYPE html> 2 <html> 3 <head> 4 <title>PHP简易计算器</title> 5 </head> 6 <body> 7 <?php 8 $mess = ""; 9 if (isset($_POST["sub"])){ 10 if ($_POST["num1"] == "") $mess .= "第一个数不能为空<br/>"; 11 else if (!is_numeric($_POST["num1"])) $mess .= "第一个数必须是数字<br/>"; 12 13 if ($_POST["num2"] == "") $mess .= "第二个数不能为空<br/>"; 14 else if (!is_numeric($_POST["num2"])) $mess .= "第二个数必须是数字<br/>"; 15 else if ($_POST["opt"]=="/" && $_POST["num2"] == 0) $mess .= "除数必须为0<br/>"; 16 } 17 18 19 ?> 20 <?php 21 //第一次访问时设置初始值 22 if (!isset($_POST["num1"]))$_POST["num1"] = "0"; 23 if (!isset($_POST["num2"]))$_POST["num2"] = "0"; 24 if (!isset($_POST["opt"]))$_POST["opt"] = "+"; 25 // echo $_POST["num1"]; 26 ?> 27 <table align ="center" width="400"> 28 <form action="" method="post"> 29 <caption><h1>计算器</h1></caption> 30 <tr> 31 <td><input type="text" size="4" name="num1" value="<?php echo $_POST["num1"]?>"/></td> 32 <td> 33 <select name="opt"> 34 <option value ="+" <?php echo $_POST["opt"]=="+"?"selected":"" ?>>+</option> 35 <option value ="-" <?php echo $_POST["opt"]=="-"?"selected":"" ?>>-</option> 36 <option value ="*" <?php echo $_POST["opt"]=="*"?"selected":"" ?>>*</option> 37 <option value ="/" <?php echo $_POST["opt"]=="/"?"selected":"" ?>>/</option> 38 </select> 39 </td> 40 <td><input type="text" size="4" name="num2" value="<?php echo $_POST["num2"]?>"/></td> 41 <td><input type="submit" name="sub" value="计算"/></td> 42 </tr> 43 44 </form> 45 <?php 46 if(isset($_POST["sub"])) { 47 echo '<tr><td colspan="4">'; 48 49 if(!$mess){ 50 $sum = 0; 51 switch ($_POST["opt"]) { 52 case "+":$sum=$_POST["num1"]+$_POST["num2"];break; 53 case "-":$sum=$_POST["num1"]-$_POST["num2"];break; 54 case "*":$sum=$_POST["num1"]*$_POST["num2"];break; 55 case "/":$sum=$_POST["num1"]/$_POST["num2"];break; 56 } 57 echo "结果: {$_POST['num1']} {$_POST['opt']} {$_POST["num2"]} = {$sum}"; 58 } else echo $mess; 59 60 echo '</td></tr>'; 61 } 62 ?> 63 </table> 64 </body> 65 </html>
执行结果
