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
জ্ঞানকোষ প্রকাশনী
৩৮/২-ক, বাংলাবাজার (২য় তলা), ঢাকা।
ফোনঃ ৭১১৮৪৪৩, ৮১১২৪৪১, ৮৬২৩২৫১.
কলকাতায় পরিবেশক/প্রাপ্তিস্থান
রিতা ইন্টারন্যাশনাল
৩৬, পি.এন. ব্যানার্জি রোড, কলকাতা
ফোনঃ ২৫১৩৮৩৫৯, ৯৮৩০৪৩৯৬৭৯, +৯১৯৮৩০৪৩৯৬৭৯