变量undefined [重复]

Question

This question already has an answer here:

• “Notice: Undefined variable”, “Notice: Undefined index”, and “Notice: Undefined offset” using PHP 28 answers

I'm setting Error Variable to contain all the errors if user left any of the input and them I'm trying to echo it out in a div but I get this message:

"Notice: Undefined variable: error in C:\xampp\htdocs\signup.php on line 202"

Although I've defined this Variable earlier in first php tags but I still get Error..

<?php 

session_start();

if(isset($_POST['signup'])){

    $fname = $_POST['fname'];
    $lname = $_POST['lname'];
    $email = $_POST['email'];
    $pass = $_POST['pass'];
    $cpass = $_POST['cpass'];

    $error="";

        if(!$fname){

        $error.="<br />Please enter your First Name";

        }

        if(!$lname){

           $error.="<br />Please enter your Last Name";

        }

        if(!$email){

            $error.="<br />Please enter your Email Adress";

        }

        if(!$pass && strlen($_POST['pass'])<8){

            $error.="<br />Please enter your Password with atleast 8 Characters.";

        }

        if(!$cpass){

            $error.="<br />Please enter your Confirmed Password";

        }

        if($pass != $cpass){

            $error.="<br />Your Passwords don't match";

        }

        if(!$error){

            $link = mysqli_connect("localhost", "root", "", "shop");

            $query = "SELECT * FROM users WHERE email='".mysqli_real_escape_string($link, $email)."'";

            $result = mysqli_query($link, $query);

            $results = mysqli_num_rows($result);

            if($results == 1){

                $error = "This Email is already Registered. Do you want to <a href='login.php'>Login </a>?";

            }else{

                $query = "INSERT INTO users (fname, lname, email, password) VALUES ('".$fname."', '".$lname."', '".mysqli_real_escape_string($link, $email)."', '".md5(md5($email).$pass)."')";

                $result = mysqli_query($link, $query);

            if($result == FALSE){

                $error = "Couldn't Connect";

            }else{

                $_SESSION['id']=mysqli_insert_id($link);

                print_r($_SESSION);

                /* Redirect to Logged In Page */

            }
        }

        }else{

            $error = "There were following error(s) in your Sign Up Details.".$error;

            echo '<div class="alert alert-danger">'.$error.'</div>';

        }

}

?>

'.$error.'';

            }

       ?>

     <form method="post" action="">

       <div class="form-group inputs">

          <span>First Name: </span><input type="text" name="fname" class="form-control" style="margin-right:20px" />

          <span>Last Name: </span><input type="text" name="lname" class="form-control" />

       </div> <!-- end form-group Div -->

       <div class="form-group inputs">

          <span>Email: </span><input type="text" style="width:350px" name="email" class="form-control" />

       </div> <!-- end form-group Div -->

       <div class="form-group inputs">

          <span style="margin-left:-33px;">Password: </span><input type="password" style="width:350px;" name="pass" class="form-control" />

       </div> <!-- end form-group Div -->

       <div class="form-group inputs">

          <span style="margin-left:-102px;">Confirm Password: </span><input type="password" style="width:350px" name="cpass" class="form-control" />

       </div> <!-- end form-group Div -->

       <div style="margin:10px auto 10px auto; width:70%; text-align:center">

          <span>By registering your Account in our Online Store, You agree to our <a href="#">Terms And Conditions</a> and Confirm that you have read our <a href="#">User Guide</a>.</span>

       </div>

       <div class="form-group center">

          <input type="submit" value="Sign Up" name="signup" class="btn btn-success btn-lg">

     </form>

</div>

Answer 1

The problem is that $error is only defined within the if (isset($_POST['signup'])) { condition.

You'll need to define it outside, or just check if it's set when you try to use it, e.g.

if (isset($error)) {

If you want to check that it's also not blank, you can do

if (isset($error) && $error !== '') {

although

if (isset($error) && $error) {

will also work, as a non-blank, non-zero value will equate to true. But I think the first option is more readable.