代码：
这里写代码片 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>网页版计算器</title> </head> <body> <?php //判断输入框是否为空 if(!empty($_POST)){ $num1=$_POST['data1']; $num2=$_POST['data2']; $jjcc=$_POST['jieguo']; $fuhao=$_POST['xllb']; //输出运算过程 print_r($_POST); //判断选择的是+ - * / switch($fuhao){ case '+': $jjcc=$num1+$num2; break; case '-': $jjcc=$num1-$num2; break; case '*': $jjcc=$num1*$num2; break; case '/': $jjcc=$num1/$num2; break; default: echo "你输入的不对，请重新输入！"; } }else{ $num1=""; $num2=""; $jjcc=""; $fuhao=""; } ?> <h1>网页版的计算器<h1> <hr/> <form id="form1" name="form1"action="" method="post"> <input name="data1" type="text" value='<?php echo $num1;?>'> <select name="xllb"> <option value="+"<?php if($fuhao=="+"){echo 'selected';}?>>+</option> <option value="-"<?php if($fuhao=="-"){echo 'selected="selected"';}?>>-</option> <option value="*"<?php if($fuhao=="*"){echo 'selected="selected"';}?>>*</option> <option value="/"<?php if($fuhao=="/"){echo 'selected="selected"';}?>>/</option></select> <input name="data2" type="text" value="<?php echo $num2;?>"> <input type="submit" value="=" > <input type="text" name="jieguo" value="<?php echo $jjcc;?>"> </form> </body> </html>