Question

php 如何限制文本只能输入数字1-30

Answer 1

<?php
    if ($_POST){
        $num = $_POST['num'];
        /*if(!is_numeric($num)){
            echo "<script>alert('必须是数字！');window.history.back();</script>";
        }elseif( strlen($num)>2 ){
            echo "<script>alert('最大两位数！');window.history.back();</script>";
        }else{} */
        if($num == ""){
            echo "<script>alert('不能为空！');window.history.back();</script>";
        }elseif(!ctype_digit($num)){
            echo "<script>alert('必须是整数！');window.history.back();</script>";
        }elseif ($num>30 || $num<1){
            echo "<script>alert('必须介于1-30之间！');window.history.back();</script>";
        }else{
            return true;
        }
    }
?>
<form action="" method="post" >
<input type="text" name="num" />
<input type="submit" value="submit" />
</form>

Answer 2

php也能有正则表达式，要不就在输入的时候用javascript判断，再有就是用不同的控件，比如select，你定义值，让用户去选择

Answer 3

if($str>=1||$str<=30){
echo "pass";
}else{
echo "超出限制！";
}

Answer 4

php限制不了，得用javascript