php变量unidentified index [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 still a beginner to php and I cannot seem to understand what's wrong here. The code still works even though there's an 'unidentified index' error. The error I get would be referring to the variables $food, $calories, $healthy, $submit.

The code is:

<?php

require 'connect.inc.php';

$foodname = $_POST['food_name'];
$calories = $_POST['calories'];
$healthy = $_POST['healthy_unhealthy'];
$submit_button = $_POST['submit'];

$sql="INSERT INTO `food` (`food`, `calories`, `healthy_unhealthy`) VALUES('$foodname', '$calories', '$healthy')";

if(isset($submit_button)&&!empty($foodname)&&!empty($calories)&&!empty($healthy))
{
    mysql_query($sql, $conn);
}
else{
echo'Kindly fill in fields';
}

?>
<form action="insert.php" method="POST">
Food Name:<br>
<input type="text" name="food_name"><br>
Calories:<br>
<input type="text" name="calories"><br>
Healthy:<br>
<input type="text" name="healthy_unhealthy"><br>
<input type="submit" name="submit">
</form>

</div>

Answer 1

First and foremost, ensure that you're in the appropriate state to be accepting the data. Wrap your code in an:

<?php

require 'connect.inc.php';

// We only run this code if the user has POSTed data to this page. Without this we 
// will get an 'undefined index' error.
if(isset($_POST['submit'])) {
    $foodname = $_POST['food_name'];
    $calories = $_POST['calories'];
    $healthy = $_POST['healthy_unhealthy'];
    $submit_button = $_POST['submit'];

    $sql="INSERT INTO `food` (`food`, `calories`, `healthy_unhealthy`) VALUES('$foodname', '$calories', '$healthy')";

    if(isset($submit_button)&&!empty($foodname)&&!empty($calories)&&!empty($healthy))
    {
        mysql_query($sql, $conn);
    }
    else{
        echo'Kindly fill in fields';
    }
}

?>
<form action="insert.php" method="POST">
Food Name:<br>
<input type="text" name="food_name"><br>
Calories:<br>
<input type="text" name="calories"><br>
Healthy:<br>
<input type="text" name="healthy_unhealthy"><br>
<input type="submit" name="submit">
</form>

This will ensure that you're currently receiving a POST request, from the form you've defined.

The $_POST variable is an array containing data you've sent to the web application via a POST request. In your form you should have fields with the appropriate names (food_name, calories, healthy_unhealthy, etc). It sounds like these fields may be missing.

In your code, somewhere near the top, put in the following:

print_r($_POST);

or, alternatively you could do a

var_dump($_POST);

This will print out the contents of your $_POST variable. If you do not see any reference to food_name, calories, or healthy_unhealthy check that your form is correct and is passing these variables to the web application.