Input and Output in Programming

Input and Output (I/O) are fundamental concepts in programming.

• Input allows a program to receive data from the user, files, or other sources, while output allows it to display results.
• I/O is essential for creating interactive programs and performing tasks with dynamic data.

Input Output in C

stdio.h is the library in C that provides functions for input and output, like printf() and scanf().

• printf() is used to display messages or values on the screen. You can print text, numbers, and variables.
• scanf() is used to read input from the user and requires a format specifier to know the type of data.
• \n is used to move to a new line so that the next output appears below the previous one.
• Format specifiers tell C what type of data to read or print, for example: %d for integers, %f for floats, %c for characters, and %s for strings.

#include <stdio.h>

int main() {
    int age;
    float height;
    char grade;
    char name[20];

    // Asking for input
    printf("Enter your age, height, grade, and name: ");

    // Reading input from the user
    scanf("%d %f %c %s", &age, &height, &grade, name);

    // Displaying the input using printf
    printf("Your age: %d\n", age);
    printf("Your height: %.2f\n", height);  // .2f for 2 decimal places
    printf("Your grade: %c\n", grade);
    printf("Your name: %s\n", name);

    return 0;
}

Input:

20 5.9 A Alice

Output:

Your age: 20
Your height: 5.90
Your grade: A
Your name: Alice

Input Output in CPP

#include <iostream> is the library in Cpp that provides input/output functions like cout and cin.

• cout is used to display messages or values on the screen. You can print text, numbers, and variables.
• cin is used to read input from the user. The variable type determines the kind of input it accepts.
• \n or endl is used to move to a new line in output.

#include <iostream>
using namespace std;

int main() {
    int age;
    float height;
    char grade;
    string name;

    cout << "Enter your age, height, grade, and name: ";
    cin >> age >> height >> grade >> name;

    cout << "Your age: " << age << "\n";
    cout << "Your height: " << height << "\n";
    cout << "Your grade: " << grade << "\n";
    cout << "Your name: " << name << "\n";

    return 0;
}

Input:

20 5.9 A Alice

Output:

Your age: 20
Your height: 5.9
Your grade: A
Your name: Alice

Input Output in Java

Scanner (from java.util.Scanner) is used for input, and System.out is used for output.

• System.out.println() displays messages or values on the screen and moves to a new line.
• System.out.print() displays messages without moving to a new line.
• Scanner.nextInt(), nextFloat(), next(), nextLine() are used to read different types of input from the user.

import java.util.Scanner;

public class GFG {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter your age, height, grade, and name: ");
        int age = sc.nextInt();
        float height = sc.nextFloat();
        char grade = sc.next().charAt(0);
        String name = sc.next();

        System.out.println("Your age: " + age);
        System.out.println("Your height: " + height);
        System.out.println("Your grade: " + grade);
        System.out.println("Your name: " + name);
    }
}

Input:

20 5.9 A Alice

Output:

Your age: 20
Your height: 5.9
Your grade: A
Your name: Alice

Input Output in Python

Python does not require a separate library for input/output; it uses built-in functions.

• print() is used to display messages or values on the screen. You can print text, numbers, or variables.
• input() is used to read input from the user as a string; type conversion (int(), float()) is used for numbers.
• \n is used inside print() to move to a new line; print() automatically moves to a new line by default

age, height, grade, name = input("Enter your age, height, grade, and name: ").split()

age = int(age)
height = float(height)
grade = grade
name = name

print("Your age:", age)
print("Your height:", height)
print("Your grade:", grade)
print("Your name:", name)

Input:

20 5.9 A Alice

Output:

Your age: 20
Your height: 5.9
Your grade: A
Your name: Alice

Input Output in C#

System namespace provides input/output functions, and Console is used for I/O.

• Console.WriteLine() displays messages or values on the screen and moves to a new line.
• Console.Write() displays messages without moving to a new line.
• Console.ReadLine() reads input from the user as a string; type conversion is needed for other types like int.Parse() or float.Parse().

using System;

class GFG {
    static void Main() {
        Console.Write("Enter your age, height, grade, and name: ");
        string[] inputs = Console.ReadLine().Split();

        int age = int.Parse(inputs[0]);
        float height = float.Parse(inputs[1]);
        char grade = char.Parse(inputs[2]);
        string name = inputs[3];

        Console.WriteLine("Your age: " + age);
        Console.WriteLine("Your height: " + height);
        Console.WriteLine("Your grade: " + grade);
        Console.WriteLine("Your name: " + name);
    }
}

Input:

20 5.9 A Alice

Output:

Your age: 20
Your height: 5.9
Your grade: A
Your name: Alice

Input Output in JavaScript

In Node.js, input/output is handled using readline module for input and console.log() for output.

• console.log() displays messages or values on the screen and moves to a new line.
• console.print() is not standard; output is mostly done via console.log().
• Input is read using readline.question() in Node.js or prompt() in browsers.

const readline = require('readline').createInterface({
  input: process.stdin,
  output: process.stdout
});

readline.question('Enter your age, height, grade, and name (space separated): ', input => {
    const [age, height, grade, name] = input.split(' ');
    console.log(`Your age: ${age}`);
    console.log(`Your height: ${height}`);
    console.log(`Your grade: ${grade}`);
    console.log(`Your name: ${name}`);
    readline.close();
});

Input:

20 5.9 A Alice

Output:

Your age: 20
Your height: 5.9
Your grade: A
Your name: Alice