What is the equivalent of C++'s define in PHP to prevent duplicate function declarations?

In PHP, the equivalent of C++'s define to prevent duplicate function declarations is using the `function_exists()` function. This function checks if a function with a specific name has already been defined, and if so, prevents redefining it. 

if (!function_exists('myFunction')) {
    function myFunction() {
        // Function implementation
    }
}

Keywords

PHP define duplicate function declarations equivalent C++

Related Questions