Input And Output Functions of C++

 Input And Output Functions of C++

·       Standard Input/Output (I/O) library streams functions.

·       Used for input and output objects.

·       Main functions are cin, cout, and cerr, etc

---

Input Function: cin

• Take input from the user by the standard input device (keyboard).
• Use the extraction operator (>>) with cin.

Syntax:

cin >> variable;

 

Example:

#include <iostream>

using namespace std;

 

int main() {

    int age;

    cout << "Enter your age: ";

    cin >> age;

    cout << "Your age is: " << age << endl;

    return 0;

}

 

Output:

Enter your age: 25

Your age is: 25

---

Output Function: cout

• Display output on the standard output device (console).
• Use the insertion operator (<<) with cout.

Syntax:

cout << "Message";

 

Example:

#include <iostream>

using namespace std;

 

int main() {

    cout << "Hello, World!" << endl;

    return 0;

}

 

Output:

Hello, World!

---

 

Error Output Function: cerr

• Cerr is used to output error messages.
• Like cout, it uses the insertion operator (<<), but it outputs to the standard error stream.

Syntax:

cerr << "Error message";

Example:

#include <iostream>

using namespace std;

 

int main() {

    cerr << "This is an error message." << endl;

    return 0;

}

Output:

This is an error message.

---

 

Formatted Input and Output

setw

·       Part of the I/O manipulators in the <iomanip> library.

·       Used to set the width of the output field for the next item displayed using cout.

 

Example:-

#include <iostream>

#include <iomanip>

using namespace std;

 

int main() {

    cout << setw(10) << "Name" << setw(5) << "Age" << endl;

    cout << setw(10) << "Alice" << setw(5) << 25 << endl;

    cout << setw(10) << "Bob" << setw(5) << 30 << endl;

    return 0;

}

 

Output:

      Name  Age

     Alice   25

       Bob   30

=================================================