C++ File Handling MCQ Quiz

The <fstream> header file contains the definitions for file stream classes like ifstream, ofstream, and fstream which are used for file operations in C++.

The ifstream (input file stream) class is specifically designed for reading from files. ofstream is for writing to files, and fstream can handle both input and output operations.

The ios::app mode opens a file for output and moves the file pointer to the end of the file, allowing you to append data without overwriting existing content.

The ios::trunc mode truncates the file to zero length if it exists, or creates the file if it doesn't exist. Combined with ofstream, it opens the file for writing and removes any existing content.

All these functions can be used to check file status: is_open() returns true if the file is open, good() returns true if no errors have occurred, and fail() returns true if an operation failed.

The get() function reads a single character from the file and returns it. read() is used for reading blocks of data, getline() reads a line of text, and extract() is not a standard file function.

The close() member function is used to explicitly close a file. While files are typically closed when the file stream object goes out of scope, it's good practice to close them explicitly when done.

The ios::binary mode flag opens the file in binary mode instead of text mode. In binary mode, data is read/written exactly as-is without any character translations (like newline conversions).

The write() function is used to write a block of binary data to a file. It takes a pointer to the data and the number of bytes to write. put() is used to write a single character.

The peek() function returns the next character in the input stream without extracting it (without moving the file pointer). This allows you to check what the next character is without reading it.

seekg() (seek get) is used to move the input position pointer, and seekp() (seek put) is used to move the output position pointer. These functions allow random access within a file.

The tellg() function returns the current position of the input (get) pointer in the file. Similarly, tellp() returns the current position of the output (put) pointer.

The eof() function returns true only after an attempt has been made to read past the end of the file. It does not return true when positioned at the last character, but only after trying to read beyond it.

The ios::ate (at end) flag opens the file and moves the file pointer to the end of the file immediately after opening. This is different from ios::app which only allows writing at the end.

Both getline() and get() with a delimiter can be used to read an entire line. getline() is specifically designed for this purpose and is more commonly used, but get() with '\n' as a delimiter can also read a line.