- PHP Call to undefined function
- 8 Answers 8
- How to reproduce the error, and how to fix it:
- How to Fix “Call to Undefined Function” in PHP?
- How Do Functions Work in PHP?
- What Are the Reasons and Solutions For The “Call to Undefined Function” Fatal Error in PHP?
- 1. Misspell of Function Name
- 2. Not Using This with Function Name Within PHP Class
- 3. Use Include or Require Properly
- 4. Using Dot(.) Instead of Object Operator(->)
- Conclusion
PHP Call to undefined function
I am not able to figure this out. Am I missing something here?
try calling a simpler function such as returning a number to triple check that your actually calling the file.
Is that the whole code of intake() ? If it is, you need to globalize the $id variable there to have access to it in that specific scope.
8 Answers 8
How to reproduce the error, and how to fix it:
function pepper() < salt(); >> $y = new yoyo(); $y->pepper(); ?> PHP Fatal error: Call to undefined function salt() in /home/el/foo/p.php on line 6 function pepper()< $this->salt(); > > $y = new yoyo(); $y->pepper(); ?> If someone could post a link to why $this has to be used before PHP functions within classes, yeah, that would be great.
$this-> refers to a function that belongs to the class and is declared within the class, same thing applies for variables declared inside the class. Inside the class it’s called $this->function(), If public outside the class it’s called $theclass->function()
Make sure you are not using $this.functionName() or self.functionName() or $self->functionName(). or variations of. Bit rusty in PHP 🙂
i was doing the mistake of not using $this->functionName(). What is understand is when you use function from same class, we need to use $this.
This was a developer mistake — a misplaced ending brace, which made the above function a nested function.
I see a lot of questions related to the undefined function error in SO. Let me note down this as an answer, in case someone else have the same issue with function scope.
Things I tried to troubleshoot first:
- Searched for the php file with the function definition in it. Verified that the file exists.
- Verified that the require (or include) statement for the above file exists in the page. Also, verified the absolute path in the require/include is correct.
- Verified that the filename is spelled correctly in the require statement.
- Echoed a word in the included file, to see if it has been properly included.
- Defined a separate function at the end of file, and called it. It worked too.
It was difficult to trace the braces, since the functions were very long — problem with legacy systems. Further steps to troubleshoot were this:
- I already defined a simple print function at the end of included file. I moved it to just above the «undefined function». That made it undefined too.
- Identified this as some scope issue.
- Used the Netbeans collapse (code fold) feature to check the function just above this one. So, the 1000 lines function above just collapsed along with this one, making this a nested function.
- Once the problem identified, cut-pasted the function to the end of file, which solved the issue.
How to Fix “Call to Undefined Function” in PHP?
The majority of new web developers see the fatal error “Call to undefined function” in PHP code, and they are unsure of the cause. If you’re one of them, then continue reading this article to the end.
We encounter the uncaught error “ Call to undefined function ” when we define and call a user-defined function. There are numerous causes for this error, and in this post, we will explore them all and provide easy explanations to dispel all of your doubts.
However, before we go into the details of this article, you need first to comprehend what a function is and what we call it. So without further ado, let’s get started with the post.
Table of Contents
How Do Functions Work in PHP?
Similar to other programming languages, PHP has functions. A function is a separate code that processes additional input as a parameter before returning a value. In PHP, we have two types of functions Builtin functions and user-defined functions .
Builtin functions are the functions that PHP provides to us to use them. Actually, you seldom ever need to build your own function because there are already more than 1000 built-in library functions available for various purposes; all you need to do is call them as needed.
On the other hand, we can create our own functions, called user-defined functions . In the case of user-defined functions, there are two key aspects you need to understand:
Creating your own PHP function is pretty simple. Let’s say you want to create a PHP function that, when called, will display a brief message in your browser. The example below invokes the method printMessage() immediately after creating it.
The name of a function should begin with the keyword “ function ,” and all PHP code should be enclosed in “ ” brackets, as seen in the example below:
// Calling a PHP Function printMessage(); ?>
What Are the Reasons and Solutions For The “Call to Undefined Function” Fatal Error in PHP?
Following are the reasons for facing the “ Uncaught Error: Call to undefined function “:
- Misspell of function
- Not using this with the function name
- Use include or require properly
- Using dot (.) instead of object operator (->)
1. Misspell of Function Name
To prevent “ Call to undefined function “, always double-check the function name. Let’s look at a straightforward example to see what output the following code will return if the function name is misspelt:
function myfunction()< $this->printMessage(); > > $myvar = new myclass(); $myvar->myfunctions(); ?>
In this example, we write myfunctions () in place of myfunction (), which causes this error, so it is always better to double-check the spelling of functions to avoid this error.
2. Not Using This with Function Name Within PHP Class
We face a “ call to an undefined function ” when we don’t use $this with the function or property name of the class. For example:
function myfunction() < printMessage(); >> $myvar = new myclass(); $myvar->myfunction(); ?>
The $this keyword in PHP refers to the class’s current object. Using the object operator (->) , the $this keyword gives you access to the current object’s attributes and methods.
Only classes have access to the $this keyword. Beyond the class, it doesn’t exist. You’ll see an error if you try to use $this outside of a class.
You only use the $ with this keyword when you want to access an object property. The property name is not used with the dollar sign ($).
We now rewrite the code that causes the abovementioned errors with this keyword and examines the results:
function myfunction()< $this->printMessage(); > > $myvar = new myclass(); $myvar->myfunction(); ?>
3. Use Include or Require Properly
When we create a namespace and include it in another file, we often face “ Call to undefined function “. For example:
include myfunction.php echo tempNamespace\printMessage(); ?>
Code of myfunction.php
To avoid this error, we have to write include or require statements correctly and in the proper place. Now we write the above code again using the appropriate include statement.
Code of myfunction.php
Most of the time, when the user doesn’t check the file name, writes the wrong namespace name, or doesn’t include the namespace correctly, then faces “ Call to undefined function ” in PHP.
4. Using Dot(.) Instead of Object Operator(->)
The PHP code syntax is different from other programming languages. So when you come from JS or any other Object Oriented language, we use the dot( . ) operator to call a method on an instance or access an instance property. But in PHP, we access the members of the provided object using the object operator ( -> ). For example:
function myfunction()< $this->printMessage(); > > $myvar = new myclass(); // Use . operator in place of object operator -> $myvar.myfunction(); ?>
We can easily get rid of this error by just replacing the dot (.) with the object operator (->) . For example:
function myfunction()< $this->printMessage(); > > $myvar = new myclass(); // Use . operator in place of object operator -> $myvar->myfunction(); ?>
Conclusion
Finally, you arrive at a point after finishing this reading when you can quickly get rid of the “ Call to undefined function “. We covered all the causes in this article and gave you all the solutions. In this circumstance, we provide you with straightforward examples to help you resolve this uncaught issue.
To summarise the article on “ How to fix call to undefined function in PHP “, always first search for the PHP file containing the function definition. Next, confirm the file’s existence and check to see if the page had the necessary (or included ) line for the file, as mentioned above. Ensure the absolute path in the require / include is accurate as well.
Double-check that the spelling of the required statement’s filename is correct. Use this keyword in class to refer to the same class function. Always check the syntax of your code; many times, users from different languages use the wrong operators.
Share this article with your fellow coders if you found it beneficial, and let us know in the comments below ⬇️ which solution you used to solve the uncaught error “Call to undefined function”.