![]() show the next character without extracting it from fileĬout << "Peek " << (char) file.peek() << endl Ĭout << "Current position is " << file. Here is an example of use member functions of fstream class: fstream file įile << "This is the first line " << endl << "This is the second line" << endl įile.seekg(ios::beg) //reset position of the inputĬout << "The next character is " << (char)next << endl seekp(int pos) – sets the position in the output sequence.int tellp() – returns position in output sequence.write (const char* str, int n) – write n characters from array of char that is pointed by str.put (char c) – write character c to file.nNumberOfBytesToRead The maximum number of bytes to be read. The caller must not use this buffer until the read operation is completed. This buffer must remain valid for the duration of the read operation. In addition, you can use the following functions to perform writing to file: A pointer to the buffer that receives the data read from a file or device. You have to use extraction (>) and insertion (> k //read an integer from file and save its value in kĬout > ) is used to write formatted data to file. It is done in the same way as you work with cout and cin objects. Therefore, you can perform basic input and output operations such as writing to file and reading from it. If you will try to call open function for a stream that is already associated with a file, it will produce an error.Īs is mentioned above, a stream is associated with a file. This line of code opens a stream that is now associated with file “test.txt” from the folder where your source file is located. open file text.txt for input and output Look on the example of opening a file for reading and writing: fstream file When you use ofstream class, default value for mode is out and the default value for ifstream class is in. It means that file is opened for reading and writing when you use fstream class. The default value for fstream mode parameter is in | out. app – all the outputs are appended to the existing contents of the file.ate – output position is set to the end of the file when a file is opened.There are different modes in which you can open a file: The second one represents mode to open a file. The first parameter represents the path to the file. Member function open of fstream class opens file and associates a stream with it: void open (const char* filename, ios_base::openmode mode = ios_base::in | ios_base::out) The first thing you need to work with file is to open it. In the case, you want only to write to file, use ofstream object. ![]() In the case, you want to open file only for input operations, you have to use ifstream object. Class fstream encapsulates both properties of ifstream and ofstream classes. In this tutorial, we will work with objects of fstream type. You have to include fstream library to be able to work with files: #include fstream – stream for both input and output operations.ifstream – stream used for input from files.ofstream – stream used for output to files.The operations on files are performed by using streams too. As you know, standard input and output operations are performed by using streams. ![]()
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