Different classes used for reading and writing to and from files are as follows:
| Classes | Description |
| ofStream | This class is used for writing onto files |
| ifStream | It is used for reading from files |
| fStream | It is used for both reading and writing onto files |
Different file opening modes in C++ are as follows:
| Modes | Description |
| ios::in | Opens a file for reading. New contents cannot be written in the file. |
| ios::out | Opens a file for writing. If file exist already then its contents are deleted but if the file does not exist it will create a new file. |
| ios::binary | It opens a file in binary form. |
| ios::truncate | Opens a file for writing. If file already exists then its previous contents are replaced with the new contents. |
| ios::app | Opens a file in append mode. It adds new content at the end of the file. |
| ios::ate | It is used to write new contents at the end of the file and we can also modify the previous contents. |
| ios::nocreate | It does not allow to create a new file if it does not exist. |
| Ios::noreplace | It does replace the old file with new file. |
A header file fstream.h is used in order to work with the files in C++ which include functions for opening and closing files.
For opening a file:
In order to open a file open() member function of fstream’s class is used.
Syntax: open (filename, mode)
Here filename is the name of the file to open and mode can be mode available in C++.
For closing a file:
In order to close a file close() member function of fstream’s class is used. This function takes no arguments.
Escape sequences are used with a ‘\’ backslash character and are used in printf statements in order to display the output of the program in a specific form. List of escape sequences:
| Character | Escape sequence
|
| Double quotation mark | \” |
| Single quotation mark | \’ |
| Question mark | \? |
| Backslash | \\ |
| Beep | \a |
| Backspace | \b |
| Formfeed | \f |
| Newlinw | \n |
| Return | \r |
| Tab | \t |