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Monday, November 6, 2017

C++ programming language part- 69 File Pointers


File Pointers

The C++ input and output system manages two integer values associated with a file. One is the get pointer, which specifies where in the file the next input or read operation will occur. the other is the put pointer,  which specifies where in the file the next output or write operation will occur. The seekg() and tellg() functions allow you to set and examine the get pointer, and seekp() and tellp() function perform these same actions on the put pointer.

The tellg() and tellp() can be used to find out the current position of the file pointer in the file. The seekg() member function takes two arguments. Suppose: Fil.seekg(10, ios::beg) means , "position the get pointer 10 bytes from the biginning of the file". The first argument is an integer specify the number also called offset . There are three referance points defined on the ios class.
@  ios::beg - the beginning of the file
@  ios::cur - the current position of the file pointer
@  ios::end - the end of the file

consider the following program, which finds out the member of records in the a file.



Program 47_6
           
            class bill
            {
              public:
                int bill_no;
                float bill_amt;
            };
       
            void main()

            {
            bill obj;
            fstream  bfil("bilfile.txt",ios::in);     // ask your faculty about fstream and o/ifstream
            bfil.seekg(0,ios::end);
            int end;
            end=bfil.tellg();
            cout<<"The size of the file is "<
            cout<<"Size of one record is "<
            int No_rce=end/sizeof(bill);
            cout<<"There are "<

        }




Part- 86 assign the content of twostring


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