Input Output Functions in C++ cplus

Input and Output Functions in C++

Introduction

Input and output (I/O) operations are essential for interacting with users. In C++, the iostream library provides cin for input and cout for output. These are part of the standard input/output stream.

Output using cout

• Used to display data on the console.

• Part of the std namespace.

Example:

#include <iostream>
using namespace std;

int main() {
    cout << "Hello, World!" << endl;
    cout << "Sum: " << 10 + 20 << endl;
    return 0;
}

Output:

Hello, World!
Sum: 30

Notes:

• << is the insertion operator.

• endl inserts a newline.

Input using cin

• Used to accept input from the user.

• Extracts data from the standard input stream.

Example:

#include <iostream>
using namespace std;

int main() {
    int age;
    cout << "Enter your age: ";
    cin >> age;
    cout << "You are " << age << " years old." << endl;
    return 0;
}

Sample Run:

Enter your age: 25
You are 25 years old.

Notes:

• >> is the extraction operator.

• Data type of variable must match the expected input.

Taking Multiple Inputs

You can accept multiple values in a single line using cin.

int a, b;
cin >> a >> b;

Using getline() for Strings

• cin stops reading at whitespace.

• Use getline() to read full lines with spaces.

#include <iostream>
#include <string>
using namespace std;

int main() {
    string name;
    cout << "Enter your full name: ";
    getline(cin, name);
    cout << "Hello, " << name << "!" << endl;
    return 0;
}

Formatting Output with iomanip

Use the <iomanip> library to format output.

#include <iostream>
#include <iomanip>
using namespace std;

int main() {
    double pi = 3.14159265;
    cout << fixed << setprecision(2) << pi << endl; // Output: 3.14
    return 0;
}

Summary

• Use cout for output and cin for input.

• Use getline() for full-line string input.

• Use iomanip for formatted output.

• Proper I/O handling is essential for user interaction and debugging.