C++ Basic Input/Output

1. Output (cout):

The cout object is used to send output to the standard output stream, usually the console. It is part of the iostream library.

#include <iostream>

int main() {
    std::cout << "Hello, World!" << std::endl;
    return 0;
}

In this example, the << operator is used to send the string "Hello, World!" to the standard output.

2. Input (cin):

The cin object is used to read input from the standard input stream, usually the console. It is also part of the iostream library.

#include <iostream>

int main() {
    int age;
    std::cout << "Enter your age: ";
    std::cin >> age;
    std::cout << "You entered: " << age << std::endl;
    return 0;
}

In this example, the >> operator is used to read an integer value from the standard input and store it in the variable age.

3. Formatting Output:

You can format the output using manipulators, as discussed earlier. For example:

#include <iostream>
#include <iomanip>

int main() {
    double pi = 3.1415926535;

    std::cout << std::fixed << std::setprecision(2) << "Value of pi: " << pi << std::endl;

    return 0;
}

This example sets the precision for floating-point output and uses fixed-point notation.

4. Reading and Writing Strings:

#include <iostream>
#include <string>

int main() {
    std::string name;

    std::cout << "Enter your name: ";
    std::getline(std::cin, name);

    std::cout << "Hello, " << name << "!" << std::endl;

    return 0;
}

Here, getline is used to read a line of text (including spaces) into the string variable name.

5. File I/O:

C++ also supports file input and output using the fstream class.

#include <iostream>
#include <fstream>

int main() {
    std::ofstream outputFile("output.txt");

    if (outputFile.is_open()) {
        outputFile << "This is a line in the file." << std::endl;
        outputFile << "Another line." << std::endl;
        outputFile.close();
    } else {
        std::cerr << "Unable to open the file." << std::endl;
    }

    return 0;
}

In this example, ofstream is used to create and write to a text file named "output.txt."

These are basic examples of input and output operations in C++. As you progress, you'll encounter more advanced features and techniques, such as error handling, binary file I/O, and custom stream manipulators.