<?php
$rea=isset($_POST['a'])?$_POST['a']:5;
$reb=isset($_POST['b'])?$_POST['b']:1;
$re1=$rea+$reb;
$re2=$rea-$reb;
$re3=$rea*$reb;
$re4=$rea/$reb;
$body='<center>※简单计算器※</center><hr><form action="index.php" method="POST">
值1:<input type="text" name="a"><br>
值2:<input type="text" name="b"><br>
<center><input type="radio" name="1" value="加" />+
<input type="radio" name="2" value="减" />-
<input type="radio" name="3" value="乘" />x
<input type="radio" name="4" value="除" />÷<br>
<input type="submit" name="submit" value="计算"></center></from>';
echo '<title>计算器</title>';
if($_POST['submit']&&$_POST['1']){
echo "我算出来了，结果是:$re1<br>$body";
}elseif($_POST['submit']&&$_POST['2']){
echo "我算出来了，结果是:$re2<br>$body";
}elseif($_POST['submit']&&$_POST['3']){
echo "我算出来了，结果是:$re3<hr>$body";
}elseif($_POST['submit']&&$_POST['4']){
echo "我算出来了，结果是:$re4<hr>$body";
}else{
echo $body;}
?>