So far in C++ we have come across iostream headers for input output purposes defining cin, cout functions. But as mentioned previously those input values were
temporary and couldn’t be used for future access. But it is never so that we
cannot store the inputted values for future access in fact the can be stored as
a whole sort of document. The procedure is popularly known as files one can define a file, can be a
text document also. As we declared a separate header file for input output
purposes in the previous section in the same way we need to declare a header
file to use a file. The header file is better known as fstream. Basically fstream
function is a predefined class type and hence its object needed to be defined
in the main function as follows:
Void main(){
Fstream f1;
F1.open(ios::out);
………
}
The above mentioned file is to open a predefined file. Where
open() is a function used to open a
file. It’s a keyword one can mention to. Similarly, to read a file we need to
use the keyword read(). Files lead
to a lot of memory leaks and so we need to close this class. Again for it we
need to use a different keyword that is close().Files
are mainly used to store information inputted by user in a document form. As
the data is inputted through the keyboard it reaches the memory from the memory
it moves to the file it is to be stored in. When the value is called to be
displayed the vice versa process takes place that is the value first moves to
the memory then the memory directs it to the monitor or the display the data to
user. This includes a lot of background process one of the most vital one is
conversion high level language to machine level language when user gives the
input and the vice versa that is machine level to high level when user asks for
display. A very good example of abstraction of data. A file can be opened in
many forms, some of them are as follows:
1.
ios::in->to
open a file in input mode
2.
ios::out->to open a file in output mode
3.
ios::binary->to
open a file in binary mode
4.
ios::ate->to
set the pointer of the file at the end
5.
ios::app->it
will write the output in the file from the end of the data without deleting the
previous ones
6.
ios::trunc->it will delete all previous
data present in file and rewrite in it
EmoticonEmoticon