PHP calls itself in an anonymous function.

//PHP closures Implement the self-invocation of functions, that is, to implement recursionfunctionClosure$n,$counter,$max){    //anonymous function, here the function of the parameter plus & symbol is, the address of the call parameter itself    $FN=function(&$n,&$counter,&$max=1) Use(&$FN){//The use parameter passes the function closure function itself        $n++; if($n<$max){//Recursive point, which is the condition of recursion            $counter.=$n.‘ <br/> '; //Call yourself recursively            $FN($n,$counter,$max); }        return $counter; };//Remember that there must be a ";" semicolon, no semicolon PHP will error, closure function    /** The return value of the function closure is the anonymous function that calls the closure * and the closure function, which refers to the parameters passed in by the closure function .*/    return $FN($n,$counter,$max); }Echo(Closure (0, ', 10));

PHP calls itself in an anonymous function.