Returns the number of arguments passed into the current user-defined function. func_num_args() will generate a warning if called from outside of a user-defined function. This function cannot be used directly as a function parameter. Instead, its result may be assigned to a variable, which can then be passed to the function.
Note: Because this function depends on the current scope to determine parameter details, it cannot be used as a function parameter. If you must pass this value, assign the results to a variable, and pass the variable.