<iostream>

<iostream> provides std::cin, std::cout, std::cerr, std::clog for standard I/O. It's the C++ way to read from stdin and write to stdout/stderr.

Use std::cout for normal output, std::cerr for errors, and std::cin for input. For formatted output, prefer std::format in C++20, but iostream is portable and widely used.

This example reads a line from standard input and echoes it back, demonstrating basic stream input/output.

// compile: g++ -std=c++11 -o iostreamexample iostreamexample.cpp
// run: ./iostreamexample
// description: reading and printing with iostream
 
#include <iostream>
#include <string>
 
int main() {
    std::cout << "enter your name: ";
    std::string name;
    std::getline(std::cin, name);
 
    std::cout << "hello, " << name << "!\n";
 
    return 0;
}