Reading and writing files in C++ - Cheat Sheet & Quick Revision

Recall & Review

beginner

What header file is needed to read from and write to files in C++?

You need to include the <fstream> header to work with file streams in C++.

beginner

How do you open a file for writing in C++?

Create an std::ofstream object and pass the filename to its constructor or use the open() method. For example:<br>std::ofstream file("example.txt");

beginner

How do you check if a file was opened successfully in C++?

Use the is_open() method on the file stream object. For example:<br>if (file.is_open()) { /* file opened */ }

beginner

What is the difference between std::ifstream and std::ofstream?

std::ifstream is used to read from files, while std::ofstream is used to write to files.

beginner

How do you read a line of text from a file in C++?

Use std::getline() with an ifstream object and a string variable. Example:<br>std::string line;<br>std::getline(file, line);

Which C++ class is used to write data to a file?

A std::ofstream

B std::ifstream

C std::fstream

D std::iostream

std::ofstream is specifically designed for writing data to files.

How do you check if a file opened successfully in C++?

A Using the open() method

B Using the is_open() method

C Using the close() method

D Using the read() method

The is_open() method returns true if the file stream is successfully opened.

Which function reads a whole line from a file into a string?

A std::getline()

B file.read()

C file.get()

D std::readline()

std::getline() reads a line from the input stream into a string.

What header must be included to use file streams in C++?

A <fstream.h>

B <iostream>

C <fstream>

D <file>

is the standard header for file stream classes.

Which class can be used for both reading and writing files?

A std::iostream

B std::ifstream

C std::ofstream

D std::fstream

std::fstream supports both input and output operations on files.

Explain how to open a file for reading and check if it opened successfully in C++.

Think about the steps from including the right header to checking the file state.

Describe how to write text to a file and then close it properly in C++.

Remember the sequence: open, write, close.