Реализовать указатель на любую из функций математических операций

#include <iostream>
 
using namespace std;
 
int plus_func(int a, int b)
{
    return a + b;
}
 
int main()
{
    int(*f)(int, int);
    f = &plus_func;
    cout << f(2, 3) << endl;
    return 0;
}

double Calc(double a, double b, double (*oper)(double,double))
{
 
    return (*oper)(a,b);
}
 
double Sum(double a, double b)
{
    return a+b;
}
 
double Sub(double a, double b)
{
    return a-b;
}
 
double Mult(double a, double b)
{
    return a*b;
}
 
double Div(double a, double b)
{
    return a/b;
}

#include <iostream> 
#include <conio.h> 
using namespace std;
 
double plus(double first_op, double second_op)
{
return first_op + second_op ;
}
 
double minus(double first_op, double second_op)
{
return first_op - second_op ;
}
 
double multiply(double first_op, double second_op)
{
return first_op * second_op ;
}
 
double divide(double first_op, double second_op)
{
return first_op / second_op ;
}
//массив указателей на функции:
double (*actions[])(double , double)={plus,minus,multiply,divide};
char *operations="+-*/";
 
double calc_it(char operation, double first_op, double second_op)
{
char * pos = strchr(operations, operation);
if(!pos)throw("Ta ne mojet byit! o_O");
int ind = pos-operations;
return (*actions[ind])(first_op, second_op);
}
void main()
{
double first_op, second_op;
char operation;
try{
cout<<"Type the first number + Enter ";
cin>>first_op;
cout<<"Press the operation symbol '+' '-' '*' or '/'  \nNo Enter requered\n";
operation=getch();
cout<<operation<<endl;
cout<<"Enter the second number + Enter  ";
cin>>second_op;
 
first_op=calc_it(operation, first_op, second_op);
cout<<" = "<<first_op<<endl;
cout<<"Well done!\n";
cout<<"Press the next operation and type the next number + Enter sequently \nOr press any non operational symbol for operation, to finish"<<endl;
while(true)
{
cout<<first_op;
operation=getch();
cout<<operation;
cin>>second_op;
first_op=calc_it(operation, first_op, second_op);
cout<<" = "<<first_op<<endl;
}
}
catch(...)
{
cerr<<"cursed life...";
}
cout<<endl;
system("pause");    
}