c++ : How do I initialize a pointer to a function?

How do I initialize a pointer to a function?
This is the way to initialize a pointer to a function
void fun(int a)
{

}

void main()
{
void (*fp)(int);
fp=fun;
fp(1);

}

Explain the scope resolution operator. 

It permits a program to reference an identifier in the global scope that has been hidden by another identifier with the same name in the local scope.

What are the differences between a C++ struct and C++ class? 
The default member and base-class access specifier are different.

How many ways are there to initialize an int with a constant? 
Two. 
There are two formats for initializers in C++ as shown in the example that follows. The first format uses the traditional C notation. The second format uses constructor notation. 
int foo = 123;
int bar (123);

How does throwing and catching exceptions differ from using setjmp and longjmp? 
The throw operation calls the destructors for automatic objects instantiated since entry to the try block.

What is a default constructor? 
Default constructor WITH arguments class B { public: B (int m = 0) : n (m) {} int n; }; int main(int argc, char *argv[]) { B b; return 0; }

What is a conversion constructor? 
A constructor that accepts one argument of a different type.

What is a mutable member? 
One that can be modified by the class even when the object of the class or the member function doing the modification is const.