Создание меню в С++

#include<iostream>
#include<fstream.h>
#include<time.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>
using namespace std;
string str;
void fun1(); 
void fun2();
int fun3();
int fun4();
void about();
 
int main()
{setlocale (LC_ALL, "Russian");
    int n, i ; ofstream dvadva("dvadva.txt"); 
     while(1) 
     { cout<<"\n1.Ñãåíåðèðîâàòü ôàéë\n2.Ïîêàçàòü ôàéë\n3.Èçìåíèòü ôàéë\n4.Çàäàòü øàáëîí\n5.Îá àâòîðå\n6.Âûõîä\n";
     cin>>n;
     switch(n)
     {case 1: fun1(); break;
     case 2: fun2(); break;
     case 3: fun3(); break;
     case 4: fun4(); break;
     case 5: about(); break;
     case 6: return 0;
     default: cout<<"Íå âûáðàí ïóíêò ìåíþ"; break;
     }
     }
}
void fun1(){ 
    int i;
    ofstream dvadva("dvadva.txt");
     srand(time(NULL));
     for (i = 0; i < 50; i++)
    dvadva <<(char)(rand()%91+32);
   cout<<"Ôàéë ñãåíåðèðîâàí!";
}
 
 
void fun2()
{ 
   ifstream input_file("dvadva.txt"); 
   char letter;
   while (!input_file.eof())
 
   { 
      letter = input_file.get(); 
      cout << letter; 
   } 
   cout<<"\n";
   cout<<"Ôàéë âûâåäåí!";
}
 
 
int fun3()
{    
    char buff[101]; int z = 0, k;
    std::string str1, str2;
    ifstream dvadva("dvadva.txt");
    dvadva.getline(buff, 101); // ñ÷èòàëè ñòðîêó èç ôàéëà
    dvadva.close();
        str1 = (const char*) buff;
         size_t len = str.length();
      size_t n = 0;
      while ((n = str1.find(str)) != string::npos)
      {str1.erase(n, len);}
      cout << str1 << endl;
    FILE *fp;
if( ( fp = fopen( "C:/Temp/dvadva.txt", "w" ) ) == NULL )
{
puts( " ×åãî-òî ÿ íå ìîãó âàø ôàéë îòêðûòü?!" );
getch();
}
fclose( fp );
ofstream write_file ("dvadva.txt");
  write_file << str1;
}    
  
 
int fun4()
{cout<<"Ââåäèòå ñòðîêó äëÿ øàáëîíà\n";
cin >> str;
    cout<<"\n";
cout<<"Øàáëîí çàäàí!";
return 0;
}
   
 
 
void about()
{cout<<"User 41";
}