<?php
$values = '';
if(!empty($_POST)){
$num1 = $_POST['num1'];
$num2 = $_POST['num2'];
$c;
$fuhao=$_POST['fuhao'];
if($fuhao=='+'){
$c=$num1+$num2;
}else if($fuhao=='-'){
$c=$num1-$num2;
}else if($fuhao=='*'){
$c=$num1*$num2;
}else if($fuhao=='/'){
$c=$num1/$num2;
}else if($fuhao=='%'){
$c=$num1%$num2;
}
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<form action='' method="post">
<input type="text" name="num1">
<select name="fuhao" id="">
<option value="+">+</option>
<option value="-">-</option>
<option value="*">*</option>
<option value="/">/</option>
<option value="%">%</option>
</select>
<input type="text" name="num2">
<input type="submit" value="=">
<input type="text" value="<?php echo $c ;?>"><br>
</form>
</body>
</html>