What common issue might occur when including a function in a separate PHP file and calling it from another file?

One common issue that might occur when including a function in a separate PHP file and calling it from another file is that the function may be redefined if the include statement is used multiple times. This can lead to a "Cannot redeclare function" error. To solve this issue, you can use the `require_once` statement instead of `include` to ensure that the file is only included once. 

// File containing the function (functions.php)
function myFunction() {
    // Function logic here
}

// File where the function is called (index.php)
require_once 'functions.php';

// Call the function
myFunction();

Keywords

PHP include function file scope

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