Write A C++ Program To Add, Subtract And Multiply Two Numbers By Using The Function Within Function Concept (Nesting Of Function).

#include<iostream.h> 
 #include<conio.h> 
  void main() 
 { 
       int x,y,z,mul(int,int); 
       clrscr(); 
       cout<<"\n Enter the value of x,y : "; 
       cin>>x>>y; 
       z=mul(x,y); 
       cout<<"\n Multiplied value is : "<<z; 
       getch(); 
 } 
       int mul(int p,int q) 
          { 
                    int s,a,add(int,int); 
                s=p*q; 
                    a=add(p,q); 
                    cout<<"\n Addition is : "<<a; 
                return(s); 
           } 
       int add(int l, int m) 
          { 
                    int b,c,sub(int,int); 
                b=l+m; 
                    c=sub(l,m); 
                    cout<<"\n Subtraction is : "<<c; 
                return(b); 
          } 
        int sub(int e, int f) 
         { 
                int d; 
                d=e-f; 
                return(d); 
          }