按键访问数组时如何避免注意未定义的索引

<?php

    $hostname='localhost';
    $username='root';
    $password='';
    $database='jsondb';

    $conn=mysqli_connect($hostname,$username,$password,$database) or die ('Connecting to Mysql failed');

     $jsonCont = file_get_contents('https://graph.facebook.com/186622721684184?fields=posts{id,full_picture,created_time,from,message}&access_token=');

     $content = json_decode($jsonCont, true);
     for($x = 0; $x <= 24; $x++){

     $id = $content['posts']['data'][$x]['id'];
     $message = $content['posts']['data'][$x]['message'];
     $name = $content['posts']['data'][$x]['from']['name'];
     $full_picture = $content['posts']['data'][$x]['full_picture'];
     $created_time = $content['posts']['data'][$x]['created_time'];

    mysqli_query($conn,"insert into fbjsontable value('$id', '$message', '$name', '$full_picture', '$created_time')");
    }

?>

this is my full code. im using fb graph data. when i post json data from graph to database, Notice: Undefined index: full_picture in C:\xampp\htdocs\event&happening\jsonCon.php on line 21 this message will be present because the full_pictures doesn't exist. How to ignore the not exist column?

First of all make sure your db field can accept null or empty values. After that you can go like this :

isset($content['posts']['data'][$x]['full_picture'])?$fullpicture=$content['posts']['data'][$x]['full_picture']:$fullpicture='';

This line of code checks if the image exists and if it does it will assign it's value to your variable $fullpicture or else will leave the variable empty.

The error is coming from the fact that your $fullpicture variable has not assigned with any value. As i said though make sure your db-field accepts empty field. If not and you don't have control over your table then go for something like:

isset($content['posts']['data'][$x]['full_picture'])?$fullpicture=$content['posts']['data'][$x]['full_picture']:$fullpicture='Image not found';

if you use php7.0+ you can avoid notice by ternary operator like this:

$full_picture = $content['posts']['data'][$x]['full_picture'] ?? null;

$full_picture will now contain sent data or null when data was not received.