1. Examine the following program. Identify and correct any errors.

   #include <fstream.h>
   int main()
   {
     ifstream in_file;
     in_file.open(input.dat);
     cout << "File opened" << endl;
     return 0;
   }

2. Write the statement required to explicitly close a file. Assume
   that the physical file name is output.dat and the stream is 
   out_file.

3. Examine the following program. You have been asked to modify this program
   so that the output is directed to the screen instead of the output file.
   Make all necessary changes.

   #include <fstream.h>
   int main()
   {
     ifstream in_file;
     ofstream out_file;
     in_file.open("input.dat");
     out_file.open("output.dat");
     int num1, num2, num3;
     in_file >> num1 >> num2 >> num3;
     out_file << "first " << num1 << " second " << num2 
              << " third " << num3 << endl;
     in_file.close();
     out_file.close();
     return 0;
   }
   
4. You are writing a program that must copy the contents of a specified file
   to the screen. Write the code necessary to prompt the user for the file 
   name and to get the name supplied. If necessary, assume the input stream 
   has been declared as in_file.

5. Examine the following program. This program has been proposed as a program
   to copy the contents of a file containing integers. Examine the program 
   carefully and comment on the contents of the output file assuming the input
   file contents below (i.e. following the program).  

   #include <fstream.h>
   int main()
   {
     ifstream in_file;
     ofstream out_file;
     in_file.open("input.dat");
     out_file.open("output.dat");
     int num1;
     while (in_file >> num1)
       out_file << num1;
     in_file.close();
     out_file.close();
     return 0;
   }
  

   10 20 30 40
   1 15 31 

6. Examine the following code fragment. What do you think would be output
   if the input file contains the characters below:
     
   abc.xyz

   char ch;
   do
   {
      in_file.get(ch);
      cout << toupper(ch);
   } while (ch != '.');

   Hint: See page 864 of your text.