C++: Store & Call the function pointers in a vector of function pointers

I've a scenario as below code. I'm trying to

1. Store the address of a C++ member function in a vector of function pointers.

2. access a C++ member function using this vector of function pointers.

I am able to add the functions, but I can't call them. The error I get is:

error: must use '.' or '->' to call pointer-to-member function in

class allFuncs {
     private:
        std::vector<void *(allFuncs::*)(int)> fp_list; // Vector of function pointers

       void func_1(int a) {
           // some code
        }

       void func_2(int a) {
           // some code
        }

        void func_3() {
           // STORING THE FUNCTION POINTER INTO The VECTOR OF FUNCTION POINTERS
           fp_list.push_back(&func_2);
           fp_list.push_back(allFuncs::func_1);      
        }

        func_4() {
          // Calling the function through the function pointer in vector
          this->*fp_list.at(0)(100);  // this does not work 
        }
}