how to use pointer -> function()

To use a pointer to a function in C++, first you need to declare the function pointer type. You can declare the function pointer type using the syntax:

return_type (*pointer_name)(arg_type1, arg_type2, ...);

Here, `return_type` is the return type of the function pointed to, `arg_type1`, `arg_type2`, etc. are the types of the function parameters, and `(*pointer_name)` declares a function pointer variable called `pointer_name`.

Once you have declared your function pointer variable, you can assign it the address of a function using the `&` operator:

pointer_name = &function_name;

To call the function using the function pointer, you need to use the dereference operator `(*pointer_name)`:

(*pointer_name)(arg1, arg2, ...);

Here, `arg1`, `arg2`, etc. are the arguments passed to the function.

In summary, to use a pointer to a function in C++, you need to declare a function pointer type, assign it the address of a function using the `&` operator, and call the function using the dereference operator `(*pointer_name)`.