File handling
- 2. .
- 4. It is a file that stores information in ASCII characters. In text files, each line of text is terminated with a special character known as EOL (End of Line) character or delimiter character. When this EOL character is read or written, certain internal translations take place. It is a file that contains information in the same format as it is held in memory. In binary files, no delimiters are used for a line and no translations occur here.
- 5. ofstream: Stream class to write on files ifstream: Stream class to read from files fstream: Stream class to both read and write from/to files.
- 6. Opening a file ofstream outFile("sample.txt"); //output only ifstream inFile(“sample.txt”); //input only Stream-object.open(“filename”, mode) ofstream outFile; outFile.open("sample.txt"); ifstream inFile; inFile.open("sample.txt");
- 8. outFile.close(); inFile.close(); put() and get() function the function put() writes a single character to the associated stream. Similarly, the function get() reads a single character form the associated stream. example : file.get(ch); file.put(ch); write() and read() function write() and read() functions write and read blocks of binary data. example: file.read((char *)&obj, sizeof(obj)); file.write((char *)&obj, sizeof(obj));
- 10. All i/o streams objects have, at least, one internal stream pointer: ifstream, like istream, has a pointer known as the get pointer that points to the element to be read in the next input operation. ofstream, like ostream, has a pointer known as the put pointer that points to the location where the next element has to be written. Finally, fstream, inherits both, the get and the put pointers, from iostream (which is itself derived from both istream and ostream).
- 11. These internal stream pointers that point to the reading or writing locations within a stream can be manipulated using the following member functions:
- 12. The other prototype for these functions is: seekg(offset, refposition ); seekp(offset, refposition ); The parameter offset represents the number of bytes the file pointer is to be moved from the location specified by the parameter refposition. The refposition takes one of the following three constants defined in the ios class. ios::beg start of the file ios::cur current position of the pointer ios::end end of the file example: file.seekg(-10, ios::cur);
- 13. File I/O is a five-step process: 1. Include the header file fstream in the program. 2. Declare file stream object. 3. Open the file with the file stream object. 4. Use the file stream object with >>, <<, or other input/output functions. 5. Close the files.
- 14. When data is stored in a file in the binary format, reading and writing data is faster because no time is lost in converting the data from one format to another format. Such files are called binary files. This following program explains how to create binary files and also how to read, write, search, delete and modify data from binary files.