developer-roadmap/src/data/roadmaps/cpp/content/iostream@VeVxZ230xkesQsIDig8zQ.md

iostream

iostream is a header in the C++ Standard Library that provides functionality for basic input and output (I/O) operations. The I/O streams facilitate communication between your program and various sources, such as the console, files, or other programs.

iostream includes the following classes:

• istream: for input operations from an input source.
• ostream: for output operations to an output target.
• iostream: a combination of istream and ostream for both input and output operations.

These classes inherit from base classes ios and ios_base.

Additionally, iostream defines several objects that are instances of these classes and represent the standard input and output streams:

• cin: an istream object to read from the standard input, typically corresponding to the keyboard.
• cout: an ostream object to write to the standard output, typically the console.
• cerr: an ostream object to write to the standard error output, typically used for displaying error messages.
• clog: an ostream object, similar to cerr, but its output can be buffered.

Here are some code examples on using iostream for input and output operations:

#include <iostream>

int main() {
    int a;
    std::cout << "Enter a number: ";
    std::cin >> a;
    std::cout << "You entered: " << a << '\n';
    return 0;
}


#include <iostream>

int main() {
    std::cerr << "An error occurred.\n";
    std::clog << "Logging information.\n";
    return 0;
}

Remember to include the iostream header when using these features:

#include <iostream>