<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<?php
$sum="";
$num1=$_POST['num1'];
$num2=$_POST['num2'];
if(is_numeric($num1) && is_numeric($num2)){
if(isset($_POST['div'])){
if($num2 ===0){
echo "除数不能为0";
}else{
$sum=$num1/$num2;
}
}
if(isset($_POST['add'])){
$sum=$num1+$num2;
}
if(isset($_POST['sub'])){
$sum=$num1-$num2;
}
if(isset($_POST['mul'])){
$sum=$num1*$num2;
}
}else{
echo "请输入有效数值";
}
?>
<form method="post" action="">
计算器<br>
数值1:<input type="text" name="num1" value="<?php echo $num1;?>"><br>
数值2:<input type="text" name="num2" value="<?php echo $num2;?>"><br>
<input type="submit" name="add" value="+">
<input type="submit" name="sub" value="-">
<input type="submit" name="mul" value="*">
<input type="submit" name="div" value="/"><br>
结果:<input type="text" name="sum" value="<?php echo $sum;?>">
</form>
</body>
</html>
追问他会说num1和num2没定义怎么办
追答$num1=isset($_POST['num1']) ? $_POST['num1'] : "";
$num2=isset($_POST['num2']) ? $_POST['num2'] : "";
追问多谢,学习了