What are the potential reasons for the "Call to undefined function" error in PHP?

The "Call to undefined function" error in PHP typically occurs when a function is being called that has not been defined or included in the current script. This can happen if the function is defined in a separate file that has not been included, or if there is a typo in the function name. To solve this issue, make sure that the function is defined and included in the script before calling it.

// Include the file containing the function definition
include 'functions.php';

// Call the function after including the file
myFunction();