Chapter 12 ndash; File Operations.ppt

Starting Out with C++ 3rd Edition, by Tony Gaddis Chapter 12 – File Operations 12.1 What is a File? A file is a collection on information, usually stored on a computer’s disk. Information can be saved to files and then later reused. 12.2 File Names All files are assigned a name that is used for identification purposes by the operating system and the user. Table 12-1 12.3 Focus on Software Engineering: The Process of Using a File Using a file in a program is a simple three-step process The file must be opened. If the file does not yet exits, opening it means creating it. Information is then saved to the file, read from the file, or both. When the program is finished using the file, the file must be closed. Figure 12-1 Figure 12-2 12.4 Setting Up a Program for File Input/Output Before file I/O can be performed, a C++ program must be set up properly. File access requires the inclusion of fstream.h 12.5 Opening a File Before data can be written to or read from a file, the file must be opened. ifstream inputFile; inputFile.open(“customer.dat”); Program 12-1 // This program demonstrates the declaration of an fstream // object and the opening of a file. #include iostream.h #include fstream.h void main(void) { fstream dataFile; // Declare file stream object char fileName[81]; cout Enter the name of a file you wish to open\n; cout or create: ; cin.getline(fileName, 81); dataFile.open(fileName, ios::out); cout The file fileName was opened.\n; } Program Output with Example Input Enter the name of a file you wish to open or create: mystuff.dat [Enter] The file mystuff.dat was opened. Table 12-3 Table 12-4 Table 12-4 continued Opening a File at Declaration fstream dataFile(“names.dat”, ios::in | ios::out); Program 12-2 // This program demonstrates the opening of a file at the // time the file stream object is declared. #include iostream.h #include fstream.h void main(void) { fstream dataFile(names.dat, ios::in | ios::out); cout The file names.dat