Sort in Ascending order then write to a file

thanks for all ur efforts..
     
 i tried to impliment  reborn_assassin's program in to my program which is below
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// AUTHOR--SAM
#include <iostream.h>
#include <fstream.h>

#include <conio.h>
//include <stdlib.h>



 fstream datafile;
 // declaring the file object so that it can communicate with the operating system

      int max=0,min=9999,i;
      float ave,sum2;
      long sum=0;
      int* contents;  // declares variable to read data from file
      char filename[16],words[80];
      double input;
      int keypress,anykey, count=0;

      void exit_prog()
      {
       cout<<"program terminated"<<endl;


      }
  //------------------- Welcom Screen Function-------------------//
      int welcome()
{
      gotoxy(15,5);
      cout<<"****************************************";
      gotoxy(15,6);
      cout<<"*\t\t   ------- COLLEGE\t     *";
      gotoxy(15,7);
      cout<<"*\t        FILE PROCESSING SYSTEM           *";
      gotoxy(15,8);
      cout<<"*\t\t PRESS C TO CONTINUE\t     *";
      gotoxy(15,9);
      cout<<"*                                      *";
      gotoxy(15,10);
      cout<<"****************************************";
      gotoxy(34,9);
      keypress=getche();
      stop:

return 0;
}
//----------------------Menu Screen Function----------------------//
int menu()
{  clrscr();
      gotoxy(15,5);
      cout<<"****************************************"<<endl;
      cout<<"\t      *\t\tFile Processing System\t     *"<<endl;
      cout<<"\t      *     \t  Please input option        *"<<endl;
      cout<<"\t      *                            \t     *"<<endl;
      cout<<"\t      * 1----------Create new data file      *"<<endl;
      cout<<"\t      * 2----------Input data to a file      *"<<endl;
      cout<<"\t      * 3----------View numbers form a file  *"<<endl;
      cout<<"\t      * 4----------Display maximum\t     *"<<endl;
      cout<<"\t      * 5----------Display minimum\t     *"<<endl;
      cout<<"\t      * 6----------Display total\t     *"<<endl;
      cout<<"\t      * 7----------Display the Average value *"<<endl;
      cout<<"\t      * 8----------Ascending sort \t     *"<<endl;
      cout<<"\t      * 9----------EXIT  \t\t     *"<<endl;
      cout<<"\t      *                            \t     *";
      gotoxy(15,18);
      cout<<"****************************************"<<endl;
      gotoxy(34,8);
      keypress=getche();

return 0;
}
//-------------OPTION 1 CREATE FILE---------------------------//
int create_file()
{
      // asking user to input name of the file to create
  cout<<"please enter the name of the file that you wish to create"<<endl;
  cout<<"use .txt as your file extension\n";

  cin>>filename;
  cout<<"\nA file named "<<filename<<" was created"<<endl;
  datafile.open(filename,ios::out);

  datafile.close(); // close file
return 0;
}


//-------------OPTION 2 INPUT DATA TO A FILE---------------------------//
int input_data()
 {

 // asking user to input name of the file to input data to
  cout<<"please enter the name of the file that you wish to input data to"<<endl;
  cout<<"please use the correct extension\n";

  cin>>filename;

       do
       {
            count++;
            datafile.open(filename,ios::app);
            clrscr();
            cout<<"input number";
            cin>>input;
            datafile<<input<<endl;
            datafile.close();
            cout<<("do you want to input another number... press anykey to continue or N to exit\n");

            keypress=getch();

            }while(keypress!=110&&keypress!=78);

            clrscr ();
            cout<<"You entered "<<count<<" numbers\n"<<endl;

return 0;

}
//-------------OPTION 3 VIEW DATA FORM A FILE---------------------------//
int view_file()
{

        // asking user to input name of the file from which the data needs to reviewed
  cout<<"please enter the name of the file which you wish to view the contents"<<endl;
  cout<<"please use the correct extension\n";
  cin>>filename;
      datafile.open(filename,ios::in);       // open numbers.txt file for reading

       while(!datafile.eof())  // keeps reading till the end of file
       {
            datafile.getline(words,80,'\n'); // read character by character form file ito words

            cout<<words<<endl;    // displays characters on the screen

       };

       datafile.close(); // close file
return 0;
};
//-------------OPTION 4 Maximum---------------------------//

int maximum()
{          contents= new int[count];
      datafile.open(filename,ios::in);       // opens numbers.txt file for reading
// displaying the contents of the file
      for(i=0;i<count;i++)  // keeps reading till the end of file
       {
            datafile>>contents[i]; // read character by character form file  ito words

            cout<<contents[i]<<endl;    // displays characters on the screen

       };

  // find and display max
      for(i=0;i<count;i++)
      {
                        if(contents[i]>max)
                              max=contents[i];
      }
      cout<<"max is "<<max<<"\n";

  datafile.close();
return 0;
}
//-------------OPTION 5 MINIMUM---------------------------//
int minimum()
{     contents= new int[count];
      datafile.open(filename,ios::in);       // opens numbers.txt file for reading
// displaying the contents of the file
      for(i=0;i<count;i++)  // keeps reading till the end of file
       {
            datafile>>contents[i]; // read character by character form file  ito words

            cout<<contents[i]<<endl;    // displays characters on the screen

       };
      //find and display min
      for(i=0;i<count;i++)
      {
            if(contents[i]<min)
                  min=contents[i];
       }
       cout<<"min is "<<min<<endl;
  datafile.close(); // close file
      return 0;
}





//-------------OPTION 6 TOTAL---------------------------//
 int total()
 {
        contents= new int[count];
      datafile.open(filename,ios::in);       // opens numbers.txt file for reading
// displaying the contents of the file
      for(i=0;i<count;i++)  // keeps reading till the end of file
       {
            datafile>>contents[i]; // read character by character form file  ito words

            cout<<contents[i]<<endl;    // displays characters on the screen

       };
  // calcualte and display sum
      for(i=0;i<count;i++)
            sum=sum+contents[i];

      cout<<"sum is "<<sum<<"\n";

      datafile.close(); // close file
 return 0;
 }

//-------------OPTION 7 AVERAGE---------------------------//
int average()
{     contents= new int[count];
      datafile.open(filename,ios::in);       // opens numbers.txt file for reading
// displaying the contents of the file
      for(i=0;i<count;i++)  // keeps reading till the end of file
       {
            datafile>>contents[i]; // read character by character form file  ito words

            cout<<contents[i]<<endl;    // displays characters on the screen

       };
      // calclate and display average
      sum=sum2;
      ave=sum2/count;
      cout<<"average is "<<ave<<endl;
      datafile.close(); // close file
return 0;
}
//-------------OPTION 8 SORT---------------------------//
int sort()
{
            char ans;
            contents= new int[count];
            int tp, i, j, total;
            total =  sizeof(contents)/4; // Meaning you can change the size of the array
            for (i=1; i<=total-1; i++)
                  {
                  for (j=i+1; j<=total; j++)
                        {
                          if (contents[i] > contents[j])
                              {
                                     tp = contents[i];
                                     contents[i] = contents[j];
                                     contents[j] = tp;
                              }
                        }
                  }
       for (i=1; i<=total; i++)
                        cout << endl << contents[i];
       cin >> ans;

return 0;
}


 //-------------MAIN PROGRAM---------------------------//

int main()
{

      welcome();
      while(keypress!=67||keypress!=99)
      {
            if (keypress==99||keypress==67)
            {
                  menu();
                  while(keypress!=49||keypress!=50||keypress!=51||keypress!=52||keypress!=53||
                              keypress!=54||keypress!=55||keypress!=56||keypress!=57)
                  {
                        if(keypress==49||keypress==50||keypress==51||keypress==52||keypress==53||
                              keypress==54||keypress==55||keypress==56||keypress==57)
                              {
                                    if(keypress==49)
                                          {            //----- OPTION 1------//
                                                clrscr();
                                                create_file();
                                                cout<<"\n\n\t\t\tPress Any Key To Return to Main Menu";
                                                anykey=getch();
                                           }
                                    if(keypress==50)
                                          {          //----- OPTION 2------//
                                          clrscr();
                                          input_data();
                                          cout<<"\n\n\t\t\tPress Any Key To Return to Main Menu";
                                          anykey=getch();
                                          }
                                    if(keypress==51)
                                          {            //----- OPTION 3------//
                                          clrscr();
                                          view_file();
                                          cout<<"\n\n\t\t\tPress Any Key To Return to Main Menu";
                                          anykey=getch();
                                          }
                                    if(keypress==52)
                                          {            //----- OPTION 4------//
                                          clrscr();
                                          maximum();
                                          cout<<"\n\n\t\t\tPress Any Key To Return to Main Menu";
                                          anykey=getch();
                                          }
                                    if(keypress==53)
                                          {           //----- OPTION 5------//
                                          clrscr();
                                          minimum();
                                          cout<<"\n\n\t\t\tPress Any Key To Return to Main Menu";
                                          anykey=getch();
                                          }
                                    if(keypress==54)
                                          {           //----- OPTION 6------//
                                          clrscr();
                                          total();
                                          cout<<"\n\n\t\t\tPress Any Key To Return to Main Menu";
                                          anykey=getch();
                                          }
                                    if(keypress==55)
                                          {          //----- OPTION 7------//
                                          clrscr();
                                          average();
                                          cout<<"\n\n\t\t\tPress Any Key To Return to Main Menu";
                                          anykey=getch();
                                          }
                                    if(keypress==56)
                                          {         //----- OPTION 8------//
                                          clrscr();
                                          sort();
                                          cout<<"\n\n\t\t\tPress Any Key To Return to Main Menu";
                                          anykey=getch();
                                          }
                                    if(keypress==57)
                                          {        //----- OPTION 9------//
                                          clrscr();
                                          cout<<"\a"<<endl;
                                          cout<<"Thank you for using our program"<<endl;
                                          cout<<"We hope you enjoyed it";

                                          cout<<"\n\n\t\t\tPress Any Key exit the program";
                                          anykey=getch();
                                          break;

                                                             //exit(0);
                                          }

                               }


                        cout<<"\a";
                        clrscr();
                        menu();
                  }// end while of menu validation
            }

            cout<<"\a";
            clrscr();
            welcome();

      }//end while of welcome validation

return 0;
}
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there are 3 problem with my program...
1) the sort code provided by reborn_Assasin---- i ttried but i could'nt integrate his proram into mine.. i tried to look for the problem but iam having difficulty.
2) the exit function dosent work..  in the opt9.. i tried to puta  break; but  it only goes back to the welcome screenn. .
also i tried to put exit(0);  there fore included stdlib.h as header.. but for no apparent reason it gives me  9 errors.. . please could soemone  provide me with a solution for this.
3) the average option---.  initially  my ave was an int .which gave me an int value. .but when i changed it to float .all it gives me is 0..
  please help
  thank you..