Dart - Standard Input Output

Dart – Standard Input Output

Last Updated : 11 May, 2020

Standard Input in Dart:

In Dart programming language, you can take standard input from the user through the console via the use of .readLineSync() function. To take input from the console you need to import a library, named dart:io from libraries of Dart.

About Stdin Class:
This class allows the user to read data from standard input in both synchronous and asynchronous ways. The method readLineSync() is one of the method use to take input from user. Refer to offical doc for other method, from here.

Taking a string input from user –

// importing dart:io file 
import 'dart:io'; 
  
void main() 
{ 
    print("Enter your name?"); 
    // Reading name of the Geek 
    String name = stdin.readLineSync(); 
  
    // Printing the name 
    print("Hello, $name! \nWelcome to GeeksforGeeks!!"); 
} 

Input:

Geek

Output:

Enter your name?
Hello, Geek! 
Welcome to GeeksforGeeks!!

Taking integer value as input –

// Importing dart:io file 
import 'dart:io'; 
  
void main() 
{ 
    // Asking for favourite number 
    print("Enter your favourite number:"); 
  
    // Scanning number 
    int n = int.parse(stdin.readLineSync()); 
  
    // Printing that number 
    print("Your favourite number is $n"); 
} 

Input:

Output:

Enter your favourite number:
Your favourite number is 1

Standard Output in Dart:

In dart, there are two ways to display output in the console:

Using print statement.
Using stdout.write() statement.

Printing Output in two different ways –

import 'dart:io'; 
  
void main() 
{ 
    // Printing in first way 
    print("Welcome to GeeksforGeeks! // printing from print statement"); 
  
    // Printing in second way 
    stdout.write("Welcome to GeeksforGeeks! // printing from stdout.write()"); 
} 

Output:

Welcome to GeeksforGeeks! // printing from print statement
Welcome to GeeksforGeeks! // printing from stdout.write()

Note:
The print() statement brings the cursor to next line while stdout.write() don’t bring the cursor to the next line, it remains in the same line.

If the print statements are switched in the above program then:
Output:

Welcome to GeeksforGeeks! // printing from stdout.write()Welcome to GeeksforGeeks! // printing from print statement

Making a simple addition program –

import 'dart:io'; 
  
void main() 
{ 
    print("-----------GeeksForGeeks-----------"); 
    print("Enter first number"); 
    int n1 = int.parse(stdin.readLineSync()); 
  
    print("Enter second number"); 
    int n2 = int.parse(stdin.readLineSync()); 
  
    // Adding them and printing them 
    int sum = n1 + n2; 
    print("Sum is $sum"); 
} 

Input:

11
12

Output:

-----------GeeksForGeeks-----------
Enter first number
Enter second number
Sum is 23

My Personal Notes

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