What is php notice undefined index

Notice: Undefined index [duplicate]

Some time ago I proposed an setor() language construct to PHP to solve this common problem. Sadly it was morphed int the new ?: syntax, which does not solve the E_NOTICE problem. Oh well.

4 Answers 4

$thread_id = isset($_GET['id']) ? intval($_GET['id']) : 0; 

Which reads as «if $_GET[‘id’] is set, set $thread_id to intval($_GET[‘id’]) , if not, set to 0»

isset() returns a boolean value: TRUE / FALSE. If you want to determine whether $_GET[«id»] is set, you need to do so in an IF-Statement, or via a ternary operator.

You’re right, Paolo. Sorry for the hasty statement on my behalf — I’m just very sensitive when I see $_GET and a query that close 😉

Only keep in mind that a php integer may have a different min/max values than mysql’s numeric values.

This error is dependent on error/warning level set in php.ini. Its good practice to use.

also: make sure you sanitize that input from the $_GET before you do that. You’re leaving yourself open to mysql injection.

ah, yes i suppose so. had to make sure intval didn’t return false on an error, leaving you with «WHERE = «. however, the fact that it returns 0 on error could be a problem if you do have records with an id of 0.

You can get rid of all notices by simply using error_reporting(4);. Another, maybe crude but working, method to suppress the notice and sanitize the variable could be:

If you do a lot of these things, you maybe want to take a look at filter_var() and put all the functionality into a separate function (eg. get_int(«id»)).

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How to solve PHP undefined index notice

Posted on Aug 02, 2022

When accessing an array in PHP, you may see a notice message that says “undefined index” as follows:

When accessing the PHP page from the browser, the following notice message appears:

The Notice: Undefined index message means that the index key you use to access an array’s value doesn’t exist.

In the above example, the array $my_arr only has the name index key. The age index is undefined.

To solve this notice message, you need to make sure that the index is defined inside the array.

The easiest way to do so is by calling the isset() function on the array index before accessing it.

Consider the example below:

 The isset() function in PHP will make sure that the age index is defined in $my_arr .

Combine it with an if condition to create a conditional block that runs when the array index is defined.

Alternatively, you can also use the null coalescing operator to provide a fallback value when the index is undefined like this:

Because the age index is undefined in the example above, the integer 29 is will be printed by the echo function.

The null coalescing operator is useful when you have a fallback value in case the first value is undefined.

Both isset and null coalescing operator also works when you are accessing form values with $_GET and $_POST global variable.

Suppose you’re accessing a PHP page with the following GET parameters:

index.php?name=nathan&age=22

The following code checks if you have a GET parameter named age :

 Or if you want to use the null coalescing operator:

   You can use the same methods with the $_POST variable.

Remove the undefined index notice

While the notice message is useful, you may want to turn it off in production environment so your visitors won’t see it.

When you don’t want the undefined index notice to appear, you can remove it by setting the error_reporting() function at the top of your PHP page.

Now your PHP compiler will not show any notice messages, but other error messages will still be shown.

The error_reporting() function works only for the page where you call the function.

To make it work for all of your PHP pages, you need to set the configuration in your php.ini file as follows:

By setting the configuration in php.ini file, all pages will not show notice messages.

Conclusion

Now you’ve learned what is an undefined index notice in PHP and how to resolve the message.

You can use the isset() function or null coalescing operator to deal with an undefined index in PHP.

You can also remove the notice message by setting the error_reporting parameter in php.ini file, or calling the error_reporting() function.

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Undefined index in PHP [duplicate]

To fix is you’ll have to check whether $_POST[‘submit’] is set:

It’s where you test to see that is isn’t there. It should be !isset($_POST[‘SUBMIT’]) . This is because the index, SUBMIT , won’t be set, thus won’t have a value such as true to pass the if(. ) . isset() checks to see if the index/variable is actually set.

 
Add Employee
 
 
 
SSN
 
 
 
 
 else < //code here >?> 

This tests, if the index is set

• Disable warning messages, by editing the setting in PHP.ini
• Add an @ sign in front of the variable name, which will suppress the error on that particular line.
• Change your code to use isset($_POST[‘SUBMIT’]) before checking it further.

Of these, the third option is definitely the best. You shouldn’t assume that any variable supplied by the user will be set as you expect; you should always check that it’s set at all, and also that it’s set to the expected values. Otherwise you are liable to be open to hacking attacks.

The first two bullet points you suggest are bad practice and I wouldn’t recommend. The only time you want to disable warnings are when you run on production. Never use @, ever. There’s always a better alternative.

@Ollie — Granted I stated that the options are available, but I didn’t recommend them; I explicitly stated that the isset() option was the one to go for.

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What is an Undefined Index PHP Error? How to Fix It?

PHP is a widely used scripting language that is mainly used for web development purposes. It is a scripting language and finds application in automating tasks that would otherwise be impossible to implement with just human intervention. Being a server-side language, it primarily takes care of things at the server’s end. Launched in 1995 for public use, it has remained a popular choice among web developers since then.

Programming is a tricky business. It is pretty normal to stumble upon errors and warnings while making a program. The same happens a lot to PHP developers, like when they face an Undefined index in PHP. However, such errors are not hard to deal with with a little bit of knowledge and guidance.

Basics to Advanced — Learn It All!

What Is an Undefined Index PHP Error?

Websites often use forms to collect data from visitors. PHP uses $GET and $POST methods for such data collection. This data is collected and saved in variables that are used by the website to work and serve the visitor further. Many a time, some fields are left blank by the user. But the website tries to refer to these fields for proceeding further. That means the PHP code tries to get the value of the field that no one has defined and thus does not exist. Quite expectedly, it does not work and raises a notice called Undefined Index in PHP.

Code:

Result:

You can fix it using the isset() function, which we will discuss further in the upcoming sections.

Undefined Index is a notice in PHP, and it is a choice of the developer to either ignore it or fix it.

How to Ignore PHP Notice: Undefined Index?

Undefined Index in PHP is a Notice generated by the language. The simplest way to ignore such a notice is to ask PHP to stop generating such notices. You can either add a small line of code at the top of the PHP page or edit the field error_reporting in the php.ini file.

1. Adding Code at the Top of the Page

A simple way to ask PHP to disable reporting of notices is to put a line of code at the beginning of the PHP page.

Code:

Or you can add the following code which stops all the error reporting,

2. Changes in php.ini

Php.ini is a configuration file and is essential for all the programs running on PHP. Open this file and find the field error_reporting. The easiest way is to use the ctrl + F shortcut key. By default, error reporting is set to E_ALL. That means all errors are reported. Change this to E_ALL & ~E_NOTICE. It means all errors except for the notices will now be reported.

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How to Fix the PHP Notice: Undefined Index?

We know the cause of the error. It occurs when we use $_GET and $_POST methods to get input, but we reference it even when it has not been set. The solution simply is to check if it has been set before referencing.

We can use the isset() function, which checks if the variable ‘is set’ or not before referencing to them. Isset() function returns True or False depending on it.

Undefined Index in PHP $_GET

When using the $_GET method, the following code might show the notice Undefined index in PHP:

Code:

As we have not set any of these variables, this code shows the Undefined Index notice.

Change it to the following code to fix this issue:

Code:

$name = » John — This is our default name»;

$age = «10 — This is our default age. Let’s leave the grade blank.»;

Result:

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We can use a single line of code like this instead.

Code:

$name = isset($_GET[‘name’]) ? $_GET[‘name’]: “John- This is our default name”;

This approach also achieves the intended goal.

Result:

Notice: Undefined Variable

PHP shows this notice when we try to use a variable even before defining it.

Code:

Result:

It can be solved either by declaring a variable global and then using isset() to see if it is set or not. It can be echoed only if it has been set. Alternatively, we can use isset(X) ? Y to set a default.

Code:

Result:

We can set it after the isset() check like this.

Code:

$name= isset($name) ? $name:»Default»;

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It shows Undefined Offset Notice in PHP when we are referring to a key in an array that has not been set for the array.

Code:

$nameArray = array(1=>’one’, 2=>’two’, 4=>’four’);

Result:

It might show an undefined array key warning for some. It means the same thing that you are trying to access an undefined array key.

It can be solved similarly like the last two cases by using isset(), arrayexists() or empty() function.

Code:

$nameArray = array(1=>’one’, 2=>’two’, 4=>’four’);

echo ‘
using array_key_exists
‘;

echo array_key_exists(3, $nameArray);

echo array_key_exists(2, $nameArray);

Result:

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Conclusion

In this article, we learned about the undefined index in PHP. However, it is just one of the many errors, warnings, and notices that a PHP developer has to deal with. If you are looking to make a career out of developing web applications and handling such errors, Simplilearn is offering a Post Graduate Program in Full stack Web Development, in partnership with Caltech CTME. Simplilearn is the world’s #1 online Bootcamp that has helped advance 2,000,000 careers through collaboration with World’s top-ranking universities.

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About the Author

Ravikiran A S

Ravikiran A S works with Simplilearn as a Research Analyst. He an enthusiastic geek always in the hunt to learn the latest technologies. He is proficient with Java Programming Language, Big Data, and powerful Big Data Frameworks like Apache Hadoop and Apache Spark.

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