Kotlin Program to Read The Number From Standard Input

In this article, we will understand how to read a number from standard input in Kotlin. The ?nextInt? method is used to read the number.

Below is a demonstration of the same

Suppose our input is

45

The desired output would be

The input value is 45

Algorithm

• Step 1 ? Start

• Step 2 ? Declare an integer: value

• Step 3 ? Define the integer

• Step 4 ? Read the values

• Step 5 ? Display the value

• Step 6 ? Stop

Example 1

In this example, we will read the number from the standard input using the Scanner(). First, we imported the java.util.Scanner to use the Scanner() for input ?

import java.util.Scanner

Then, a scanner object is created in the main() function ?

val input_scanner = Scanner(System.`in`)

The user enters the input using the System.`in`. After that, the nextLine() method reads the string value from the user ?

var input_string:String = input_scanner.nextLine()

Let us now see the complete example ?

<div class="execute"></div><div class="code-mirror  language-kotlin" contenteditable="plaintext-only" spellcheck="false" style="outline: none; overflow-wrap: break-word; overflow-y: auto; white-space: pre-wrap;"><span class="token keyword">import</span> java<span class="token punctuation">.</span>util<span class="token punctuation">.</span>Scanner

<span class="token keyword">fun</span> <span class="token function">main</span><span class="token punctuation">(</span>args<span class="token operator">:</span> Array<span class="token operator"><</span>String<span class="token operator">></span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
   System<span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"The required packages have been imported<br>"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
   <span class="token keyword">val</span> input_scanner <span class="token operator">=</span> <span class="token function">Scanner</span><span class="token punctuation">(</span>System<span class="token punctuation">.</span>`<span class="token keyword">in</span>`<span class="token punctuation">)</span>
   <span class="token function">print</span><span class="token punctuation">(</span><span class="token string">"Enter an integer: "</span><span class="token punctuation">)</span>

   <span class="token keyword">var</span> input_integer<span class="token operator">:</span>Int <span class="token operator">=</span> input_scanner<span class="token punctuation">.</span><span class="token function">nextInt</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
   <span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"The value is: <span class="token interpolation variable">$input_integer</span>"</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>
</div><div class="output-wrapper"><div class="console-close"></div><div class="code-output"></div></div>

Output

The required packages have been imported
Enter an integer:45
The value is:5

Example 2

Here, we will create a custom function to read the number from the standard input using the Scanner ?

<div class="execute"></div><div class="code-mirror  language-kotlin" contenteditable="plaintext-only" spellcheck="false" style="outline: none; overflow-wrap: break-word; overflow-y: auto; white-space: pre-wrap;"><span class="token keyword">import</span> java<span class="token punctuation">.</span>util<span class="token punctuation">.</span>Scanner

<span class="token keyword">fun</span> <span class="token function">scan_value</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
   <span class="token keyword">val</span> input_scanner <span class="token operator">=</span> <span class="token function">Scanner</span><span class="token punctuation">(</span>System<span class="token punctuation">.</span>`<span class="token keyword">in</span>`<span class="token punctuation">)</span>
   <span class="token function">print</span><span class="token punctuation">(</span><span class="token string">"Enter an integer: "</span><span class="token punctuation">)</span>
   <span class="token keyword">var</span> input_integer<span class="token operator">:</span>Int <span class="token operator">=</span> input_scanner<span class="token punctuation">.</span><span class="token function">nextInt</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
   <span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"The value is: <span class="token interpolation variable">$input_integer</span>"</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>

<span class="token keyword">fun</span> <span class="token function">main</span><span class="token punctuation">(</span>args<span class="token operator">:</span> Array<span class="token operator"><</span>String<span class="token operator">></span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
   System<span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"The required packages have been imported<br>"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
   <span class="token function">scan_value</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>
</div><div class="output-wrapper"><div class="console-close"></div><div class="code-output"></div></div>

Output

The required packages have been imported

Enter an integer:45
The value is: 45