array_map

Name:array_map

Category:Array

Programming Language:php

One-line Description:Send each value in the array to a user-defined function and return a new value.

Example

Example 1

Apply the function to each value in the array, multiplying each value by itself, and returning an array with the new value:

 <span class="token php language-php"><span class="token delimiter important"><?php</span>
<span class="token keyword">function</span> <span class="token function-definition function">myfunction</span> <span class="token punctuation">(</span> <span class="token variable">$v</span> <span class="token punctuation">)</span>
<span class="token punctuation">{</span>
  <span class="token keyword">return</span> <span class="token punctuation">(</span> <span class="token variable">$v</span> <span class="token operator">*</span> <span class="token variable">$v</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token punctuation">}</span>

<span class="token variable">$a</span> <span class="token operator">=</span> <span class="token keyword">array</span> <span class="token punctuation">(</span> <span class="token number">1</span> <span class="token punctuation">,</span> <span class="token number">2</span> <span class="token punctuation">,</span> <span class="token number">3</span> <span class="token punctuation">,</span> <span class="token number">4</span> <span class="token punctuation">,</span> <span class="token number">5</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token function">print_r</span> <span class="token punctuation">(</span><span class="token function"></span></span><mark> <span class="token function">array_map</span> <span class="token punctuation">(</span> <span class="token string double-quoted-string">"myfunction"</span> <span class="token punctuation">,</span> <span class="token variable">$a</span> <span class="token punctuation">)</span></mark><span class="token punctuation"></span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token delimiter important">?></span>

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Example 2

Use user-defined functions to change the value of an array:

 <span class="token php language-php"><span class="token delimiter important"><?php</span>
<span class="token keyword">function</span> <span class="token function-definition function">myfunction</span> <span class="token punctuation">(</span> <span class="token variable">$v</span> <span class="token punctuation">)</span>
<span class="token punctuation">{</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span> <span class="token variable">$v</span> <span class="token operator">===</span> <span class="token string double-quoted-string">"Dog"</span> <span class="token punctuation">)</span>
  <span class="token punctuation">{</span>
  <span class="token keyword">return</span> <span class="token string double-quoted-string">"Fido"</span> <span class="token punctuation">;</span>
  <span class="token punctuation">}</span>
<span class="token keyword">return</span> <span class="token variable">$v</span> <span class="token punctuation">;</span>
<span class="token punctuation">}</span>

<span class="token variable">$a</span> <span class="token operator">=</span> <span class="token keyword">array</span> <span class="token punctuation">(</span> <span class="token string double-quoted-string">"Horse"</span> <span class="token punctuation">,</span> <span class="token string double-quoted-string">"Dog"</span> <span class="token punctuation">,</span> <span class="token string double-quoted-string">"Cat"</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token function">print_r</span> <span class="token punctuation">(</span><span class="token function"></span></span><mark> <span class="token function">array_map</span> <span class="token punctuation">(</span> <span class="token string double-quoted-string">"myfunction"</span> <span class="token punctuation">,</span> <span class="token variable">$a</span> <span class="token punctuation">)</span></mark><span class="token punctuation"></span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token delimiter important">?></span>

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Example 3

Use two arrays:

 <span class="token php language-php"><span class="token delimiter important"><?php</span>
<span class="token keyword">function</span> <span class="token function-definition function">myfunction</span> <span class="token punctuation">(</span> <span class="token variable">$v1</span> <span class="token punctuation">,</span> <span class="token variable">$v2</span> <span class="token punctuation">)</span>
<span class="token punctuation">{</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span> <span class="token variable">$v1</span> <span class="token operator">===</span> <span class="token variable">$v2</span> <span class="token punctuation">)</span>
  <span class="token punctuation">{</span>
  <span class="token keyword">return</span> <span class="token string double-quoted-string">"same"</span> <span class="token punctuation">;</span>
  <span class="token punctuation">}</span>
<span class="token keyword">return</span> <span class="token string double-quoted-string">"different"</span> <span class="token punctuation">;</span>
<span class="token punctuation">}</span>

<span class="token variable">$a1</span> <span class="token operator">=</span> <span class="token keyword">array</span> <span class="token punctuation">(</span> <span class="token string double-quoted-string">"Horse"</span> <span class="token punctuation">,</span> <span class="token string double-quoted-string">"Dog"</span> <span class="token punctuation">,</span> <span class="token string double-quoted-string">"Cat"</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token variable">$a2</span> <span class="token operator">=</span> <span class="token keyword">array</span> <span class="token punctuation">(</span> <span class="token string double-quoted-string">"Cow"</span> <span class="token punctuation">,</span> <span class="token string double-quoted-string">"Dog"</span> <span class="token punctuation">,</span> <span class="token string double-quoted-string">"Rat"</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token function">print_r</span> <span class="token punctuation">(</span><span class="token function"></span></span><mark> <span class="token function">array_map</span> <span class="token punctuation">(</span> <span class="token string double-quoted-string">"myfunction"</span> <span class="token punctuation">,</span> <span class="token variable">$a1</span> <span class="token punctuation">,</span> <span class="token variable">$a2</span> <span class="token punctuation">)</span></mark><span class="token punctuation"></span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token delimiter important">?></span>

Try it yourself

Example 4

Change all letters of the value in the array to capitalize:

 <span class="token php language-php"><span class="token delimiter important"><?php</span>
<span class="token keyword">function</span> <span class="token function-definition function">myfunction</span> <span class="token punctuation">(</span> <span class="token variable">$v</span> <span class="token punctuation">)</span>
<span class="token punctuation">{</span>
<span class="token variable">$v</span> <span class="token operator">=</span> <span class="token function">strtoupper</span> <span class="token punctuation">(</span> <span class="token variable">$v</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
  <span class="token keyword">return</span> <span class="token variable">$v</span> <span class="token punctuation">;</span>
<span class="token punctuation">}</span>

<span class="token variable">$a</span> <span class="token operator">=</span> <span class="token keyword">array</span> <span class="token punctuation">(</span> <span class="token string double-quoted-string">"Animal"</span> <span class="token operator">=></span> <span class="token string double-quoted-string">"horse"</span> <span class="token punctuation">,</span> <span class="token string double-quoted-string">"Type"</span> <span class="token operator">=></span> <span class="token string double-quoted-string">"mammal"</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token function">print_r</span> <span class="token punctuation">(</span> <span class="token function">array_map</span> <span class="token punctuation">(</span> <span class="token string double-quoted-string">"myfunction"</span> <span class="token punctuation">,</span> <span class="token variable">$a</span> <span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token delimiter important">?></span></span>

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Example 5

When assigning the function name to null:

 <span class="token php language-php"><span class="token delimiter important"><?php</span>
<span class="token variable">$a1</span> <span class="token operator">=</span> <span class="token keyword">array</span> <span class="token punctuation">(</span> <span class="token string double-quoted-string">"Dog"</span> <span class="token punctuation">,</span> <span class="token string double-quoted-string">"Cat"</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token variable">$a2</span> <span class="token operator">=</span> <span class="token keyword">array</span> <span class="token punctuation">(</span> <span class="token string double-quoted-string">"Puppy"</span> <span class="token punctuation">,</span> <span class="token string double-quoted-string">"Kitten"</span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token function">print_r</span> <span class="token punctuation">(</span><span class="token function"></span></span><mark> <span class="token function">array_map</span> <span class="token punctuation">(</span> <span class="token constant">null</span> <span class="token punctuation">,</span> <span class="token variable">$a1</span> <span class="token punctuation">,</span> <span class="token variable">$a2</span> <span class="token punctuation">)</span></mark><span class="token punctuation"></span> <span class="token punctuation">)</span> <span class="token punctuation">;</span>
<span class="token delimiter important">?></span>

Try it yourself