Swift program to Print Diamond Star Pattern

This tutorial will discuss how to write swift program to print diamond star pattern.

Star pattern is a sequence of "*" which is used to develop different patterns or shapes like pyramid, rectangle, cross, etc. These star patterns are generally used to understand or practice the program flow controls, also they are good for logical thinking.

To create a diamond star pattern, we can use any of the following methods ?

• Using nested for loop

• Using init() Function

• Using stride Function

Here we divide the diamond in two portions upper half pyramid and lower half pyramid to solve the problem.

Below is a demonstration of the same ?

Input

Suppose our given input is ?

Num = 5

Output

The desired output would be ?

        * 
      * * * 
    * * * * * 
  * * * * * * * 
* * * * * * * * * 
  * * * * * * * 
    * * * * * 
      * * * 
        * 

Method 1 - Using Nested For Loop

We can create a diamond star pattern or any other pattern using nested for loops. Here each for loop handle different tasks like holding rows, columns, whitespaces, etc.

Example

The following program shows how to print diamond star pattern using nested for loop.

<div class="execute"></div><div class="code-mirror  language-javascript" 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> Foundation
<span class="token keyword">import</span> Glibc

<span class="token comment">// Length of the triangle pattern</span>
<span class="token keyword">let</span> num <span class="token operator">=</span> <span class="token number">5</span>

<span class="token comment">// Upper pyramid</span>
<span class="token comment">// Outer for loop is used to handle the</span>
<span class="token comment">// total number of rows in upper pyramid</span>
<span class="token keyword">for</span> i <span class="token keyword">in</span> <span class="token number">1.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>num<span class="token punctuation">{</span>
   
   <span class="token comment">// Nested for loop is used to print white</span>
   <span class="token comment">// spaces</span>
   <span class="token keyword">for</span> _ <span class="token keyword">in</span> <span class="token number">0.</span><span class="token punctuation">.</span><span class="token operator"><</span><span class="token punctuation">(</span>num<span class="token operator">-</span>i<span class="token punctuation">)</span><span class="token punctuation">{</span>
      <span class="token function">print</span><span class="token punctuation">(</span><span class="token string">" "</span><span class="token punctuation">,</span> terminator<span class="token operator">:</span> <span class="token string">" "</span><span class="token punctuation">)</span>
   <span class="token punctuation">}</span>
   
   <span class="token comment">// Nested for loop is used to print upper pyramid of "*"</span>
   <span class="token keyword">for</span> _ <span class="token keyword">in</span> <span class="token number">1.</span><span class="token punctuation">.</span><span class="token number">.2</span><span class="token operator">*</span>i<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">{</span>
      <span class="token function">print</span><span class="token punctuation">(</span><span class="token string">"*"</span><span class="token punctuation">,</span> terminator<span class="token operator">:</span> <span class="token string">" "</span><span class="token punctuation">)</span>
   <span class="token punctuation">}</span>
   
   <span class="token comment">// Add new line</span>
   <span class="token function">print</span><span class="token punctuation">(</span><span class="token string">""</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>

<span class="token comment">// lower pyramid</span>
<span class="token comment">// Outer for loop is used to handle the</span>
<span class="token comment">// total number of rows in lower pyramid</span>
<span class="token keyword">for</span> i <span class="token keyword">in</span> <span class="token number">1.</span><span class="token punctuation">.</span><span class="token operator"><</span>num<span class="token punctuation">{</span>
   
   <span class="token comment">// Nested for loop is used to print white</span>
   <span class="token comment">// spaces</span>
   <span class="token keyword">for</span> _ <span class="token keyword">in</span> <span class="token number">1.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>i<span class="token punctuation">{</span>
      <span class="token function">print</span><span class="token punctuation">(</span><span class="token string">" "</span><span class="token punctuation">,</span> terminator<span class="token operator">:</span> <span class="token string">" "</span><span class="token punctuation">)</span>
   <span class="token punctuation">}</span>
   
   <span class="token comment">// Nested for loop is used to print lower pyramid of "*"</span>
   <span class="token keyword">for</span> _ <span class="token keyword">in</span> <span class="token number">1.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token operator">*</span>num <span class="token operator">-</span> <span class="token number">2</span><span class="token operator">*</span>i <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
      <span class="token function">print</span><span class="token punctuation">(</span><span class="token string">"*"</span><span class="token punctuation">,</span> terminator<span class="token operator">:</span> <span class="token string">" "</span><span class="token punctuation">)</span>
   <span class="token punctuation">}</span>
   
   <span class="token comment">// Add new line</span>
   <span class="token function">print</span><span class="token punctuation">(</span><span class="token string">""</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

        * 
      * * * 
    * * * * * 
  * * * * * * * 
* * * * * * * * * 
  * * * * * * * 
    * * * * * 
      * * * 
        * 

Method 2 - Using init() Function

Swift provide an in-built function named String.init(). Using this function we can able to create any pattern. String.init() function create a string in which the given character is repeated the specified number of times.

Syntax

Following is the syntax ?

String.init(repeating:Character, count: Int)

Here, repeating represent the character which this method repeats and count represent the total number of time the given character repeat in the resultant string.

Example

The following program shows how to print diamond star pattern using string.init() function.

<div class="execute"></div><div class="code-mirror  language-javascript" 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> Foundation
<span class="token keyword">import</span> Glibc

<span class="token comment">// Length of the diamond</span>
<span class="token keyword">var</span> num <span class="token operator">=</span> <span class="token number">8</span>
<span class="token keyword">var</span> x <span class="token operator">=</span> <span class="token number">1</span>

<span class="token comment">// Handle the rows of the diamond</span>
<span class="token keyword">while</span> x <span class="token operator"><=</span> num<span class="token punctuation">{</span>
   
   <span class="token comment">// For upper half of the diamond</span>
   <span class="token comment">// Checking for even length</span>
   <span class="token keyword">if</span> num<span class="token operator">%</span><span class="token number">2</span> <span class="token operator">==</span> <span class="token number">0</span><span class="token punctuation">{</span>
      <span class="token keyword">if</span> x <span class="token operator"><=</span> num<span class="token operator">/</span><span class="token number">2</span><span class="token punctuation">{</span>
         <span class="token keyword">let</span> mystar <span class="token operator">=</span> String<span class="token punctuation">.</span><span class="token function">init</span><span class="token punctuation">(</span>repeating<span class="token operator">:</span> <span class="token string">"*"</span><span class="token punctuation">,</span> count<span class="token operator">:</span><span class="token punctuation">(</span>x<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token operator">*</span><span class="token number">2</span><span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">)</span>
         <span class="token keyword">let</span> spaceing <span class="token operator">=</span> String<span class="token punctuation">.</span><span class="token function">init</span><span class="token punctuation">(</span>repeating<span class="token operator">:</span> <span class="token string">" "</span><span class="token punctuation">,</span> count<span class="token operator">:</span><span class="token punctuation">(</span><span class="token punctuation">(</span>num<span class="token operator">/</span><span class="token number">2</span><span class="token punctuation">)</span><span class="token operator">-</span>x<span class="token punctuation">)</span><span class="token punctuation">)</span>
         <span class="token function">print</span><span class="token punctuation">(</span>spaceing<span class="token operator">+</span>mystar<span class="token punctuation">)</span>
      <span class="token punctuation">}</span>
   <span class="token punctuation">}</span>
   
   <span class="token comment">// Checking for odd length</span>
   <span class="token keyword">else</span><span class="token punctuation">{</span>
      <span class="token keyword">if</span> x <span class="token operator"><</span> num<span class="token operator">/</span><span class="token number">2</span><span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">{</span>
         <span class="token keyword">let</span> mystars <span class="token operator">=</span> String<span class="token punctuation">.</span><span class="token function">init</span><span class="token punctuation">(</span>repeating<span class="token operator">:</span> <span class="token string">"*"</span><span class="token punctuation">,</span> count<span class="token operator">:</span><span class="token punctuation">(</span>x<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token operator">*</span><span class="token number">2</span><span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">)</span>
         <span class="token keyword">let</span> myspace <span class="token operator">=</span> String<span class="token punctuation">.</span><span class="token function">init</span><span class="token punctuation">(</span>repeating<span class="token operator">:</span> <span class="token string">" "</span><span class="token punctuation">,</span> count<span class="token operator">:</span><span class="token punctuation">(</span><span class="token punctuation">(</span>num<span class="token operator">/</span><span class="token number">2</span><span class="token punctuation">)</span><span class="token operator">-</span>x<span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
         <span class="token function">print</span><span class="token punctuation">(</span>myspace<span class="token operator">+</span>mystars<span class="token punctuation">)</span>
      <span class="token punctuation">}</span>
   <span class="token punctuation">}</span>
   
   <span class="token comment">// For lower half of the diamond</span>
   <span class="token keyword">if</span> x <span class="token operator">></span> num<span class="token operator">/</span><span class="token number">2</span><span class="token punctuation">{</span>
      <span class="token keyword">let</span> star <span class="token operator">=</span> String<span class="token punctuation">.</span><span class="token function">init</span><span class="token punctuation">(</span>repeating<span class="token operator">:</span> <span class="token string">"*"</span><span class="token punctuation">,</span> count<span class="token operator">:</span><span class="token punctuation">(</span>num<span class="token operator">-</span>x<span class="token punctuation">)</span><span class="token operator">*</span><span class="token number">2</span><span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">)</span>
      <span class="token keyword">let</span> mspace <span class="token operator">=</span> String<span class="token punctuation">.</span><span class="token function">init</span><span class="token punctuation">(</span>repeating<span class="token operator">:</span> <span class="token string">" "</span><span class="token punctuation">,</span> count<span class="token operator">:</span><span class="token punctuation">(</span>x<span class="token operator">-</span><span class="token punctuation">(</span><span class="token punctuation">(</span>num<span class="token operator">/</span><span class="token number">2</span><span class="token punctuation">)</span><span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
      <span class="token function">print</span><span class="token punctuation">(</span>mspace<span class="token operator">+</span>star<span class="token punctuation">)</span>
   <span class="token punctuation">}</span>
   x<span class="token operator">+=</span><span class="token number">1</span>
<span class="token punctuation">}</span>
</div><div class="output-wrapper"><div class="console-close"></div><div class="code-output"></div></div>

Output

   *
  ***
 *****
*******
*******
 *****
  ***
   *

Method 3 - Using stride Function

Swift provide an in-built function named stride(). The stride() function is used to move from one value to another with increment or decrement. Or we can say stride() function return a sequence from the starting value but not include end value and each value in the given sequence is steps by the given amount.

Syntax

Following is the syntax ?

stride(from:startValue, to: endValue, by:count)

Here,

from ? Represent the starting value to use for the given sequence.

to ? Represent the end value to limit the given sequence

by ? Represent the amount to step by with each iteration, here positive value represents upward iteration or increment and negative value represent the downward iteration or decrement.

Example

The following program shows how to print diamond star pattern using stride() function.

<div class="execute"></div><div class="code-mirror  language-javascript" 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> Foundation
<span class="token keyword">import</span> Glibc

<span class="token comment">// Length of the diamond</span>
<span class="token keyword">var</span> num <span class="token operator">=</span> <span class="token number">8</span>

<span class="token comment">// Print the upper half of the diamond</span>
<span class="token keyword">for</span> x <span class="token keyword">in</span> <span class="token number">1.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>num<span class="token punctuation">{</span>
   <span class="token keyword">if</span> x <span class="token operator">%</span> <span class="token number">2</span> <span class="token operator">!=</span> <span class="token number">0</span><span class="token punctuation">{</span>
   
      <span class="token comment">// Print white spaces</span>
      <span class="token keyword">for</span> _ <span class="token keyword">in</span> <span class="token function">stride</span><span class="token punctuation">(</span><span class="token parameter">from<span class="token operator">:</span> num<span class="token punctuation">,</span> to<span class="token operator">:</span> x<span class="token punctuation">,</span> by<span class="token operator">:</span> <span class="token operator">-</span><span class="token number">1</span></span><span class="token punctuation">)</span><span class="token punctuation">{</span>
         <span class="token function">print</span><span class="token punctuation">(</span>terminator <span class="token operator">:</span> <span class="token string">" "</span><span class="token punctuation">)</span>
      <span class="token punctuation">}</span>
      
      <span class="token comment">// Print star pattern</span>
      <span class="token keyword">for</span> _ <span class="token keyword">in</span> <span class="token number">1.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>x<span class="token punctuation">{</span>
         <span class="token function">print</span><span class="token punctuation">(</span><span class="token string">"*"</span><span class="token punctuation">,</span> terminator <span class="token operator">:</span> <span class="token string">" "</span><span class="token punctuation">)</span>
      <span class="token punctuation">}</span>
      <span class="token function">print</span><span class="token punctuation">(</span><span class="token string">""</span><span class="token punctuation">)</span>
   <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token comment">// Print the lower half of the diamond</span>
<span class="token keyword">for</span> x <span class="token keyword">in</span> <span class="token function">stride</span><span class="token punctuation">(</span><span class="token parameter">from<span class="token operator">:</span> num<span class="token punctuation">,</span> to<span class="token operator">:</span> <span class="token number">1</span><span class="token punctuation">,</span> by<span class="token operator">:</span> <span class="token operator">-</span><span class="token number">1</span></span><span class="token punctuation">)</span><span class="token punctuation">{</span>
   <span class="token keyword">if</span> x <span class="token operator">%</span> <span class="token number">2</span> <span class="token operator">!=</span> <span class="token number">0</span><span class="token punctuation">{</span>
   
      <span class="token comment">// Print white spaces</span>
      <span class="token keyword">for</span> _ <span class="token keyword">in</span> <span class="token function">stride</span><span class="token punctuation">(</span><span class="token parameter">from<span class="token operator">:</span> num<span class="token punctuation">,</span> to<span class="token operator">:</span> x<span class="token operator">-</span><span class="token number">2</span><span class="token punctuation">,</span> by<span class="token operator">:</span> <span class="token operator">-</span><span class="token number">1</span></span><span class="token punctuation">)</span><span class="token punctuation">{</span>
         <span class="token function">print</span><span class="token punctuation">(</span>terminator <span class="token operator">:</span> <span class="token string">" "</span><span class="token punctuation">)</span>
      <span class="token punctuation">}</span>
      
      <span class="token comment">// Print star pattern</span>
      <span class="token keyword">for</span> _ <span class="token keyword">in</span> <span class="token function">stride</span><span class="token punctuation">(</span><span class="token parameter">from<span class="token operator">:</span> <span class="token number">2</span><span class="token punctuation">,</span> to<span class="token operator">:</span> x<span class="token punctuation">,</span> by<span class="token operator">:</span> <span class="token number">1</span></span><span class="token punctuation">)</span><span class="token punctuation">{</span>
         <span class="token function">print</span><span class="token punctuation">(</span><span class="token string">"*"</span><span class="token punctuation">,</span> terminator <span class="token operator">:</span> <span class="token string">" "</span><span class="token punctuation">)</span>
      <span class="token punctuation">}</span>
      <span class="token function">print</span><span class="token punctuation">(</span><span class="token string">""</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

       * 
     * * * 
   * * * * * 
 * * * * * * * 
   * * * * * 
     * * * 
       *