用strval 和array_map 函數如何快速轉換數組中所有元素類型？

gitbox 2025-07-28

1. strval函數介紹

strval函數是PHP 內置的一個函數，用於將任意類型的值轉換為字符串類型。其語法如下：

 <span><span><span class="hljs-title function_ invoke__">strval</span></span><span>(</span><span><span class="hljs-keyword">mixed</span></span><span> </span><span><span class="hljs-variable">$var</span></span><span>): </span><span><span class="hljs-keyword">string</span></span><span>
</span></span>

其中， $var可以是任何類型的數據， strval函數將返回該值的字符串表示。如果值本身已經是字符串， strval將直接返回該值。

例如：

 <span><span><span class="hljs-variable">$var1</span></span><span> = </span><span><span class="hljs-number">123</span></span><span>;
</span><span><span class="hljs-variable">$var2</span></span><span> = </span><span><span class="hljs-number">3.14</span></span><span>;
</span><span><span class="hljs-variable">$var3</span></span><span> = </span><span><span class="hljs-literal">true</span></span><span>;

</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-title function_ invoke__">strval</span></span><span>(</span><span><span class="hljs-variable">$var1</span></span><span>); </span><span><span class="hljs-comment">// 輸出 "123"</span></span><span>
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-title function_ invoke__">strval</span></span><span>(</span><span><span class="hljs-variable">$var2</span></span><span>); </span><span><span class="hljs-comment">// 輸出 "3.14"</span></span><span>
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-title function_ invoke__">strval</span></span><span>(</span><span><span class="hljs-variable">$var3</span></span><span>); </span><span><span class="hljs-comment">// 輸出 "1"</span></span><span>
</span></span>

2. array_map函數介紹

array_map函數用於將回調函數應用到數組的每個元素上，並返回一個新數組。其語法如下：

 <span><span><span class="hljs-title function_ invoke__">array_map</span></span><span>(</span><span><span class="hljs-keyword">callable</span></span><span> </span><span><span class="hljs-variable">$callback</span></span><span>, </span><span><span class="hljs-keyword">array</span></span><span> </span><span><span class="hljs-variable">$array</span></span><span>, </span><span><span class="hljs-keyword">array</span></span><span> ...</span><span><span class="hljs-variable">$arrays</span></span><span>): </span><span><span class="hljs-keyword">array</span></span><span>
</span></span>

$callback是回調函數， $array是要操作的數組。如果有多個數組作為參數傳入， $callback函數會根據這些數組的元素依次操作。

簡單示例：

 <span><span><span class="hljs-variable">$nums</span></span><span> = [</span><span><span class="hljs-number">1</span></span><span>, </span><span><span class="hljs-number">2</span></span><span>, </span><span><span class="hljs-number">3</span></span><span>, </span><span><span class="hljs-number">4</span></span><span>];
</span><span><span class="hljs-variable">$squared</span></span><span> = </span><span><span class="hljs-title function_ invoke__">array_map</span></span><span>(fn(</span><span><span class="hljs-variable">$num</span></span><span>) =&gt; </span><span><span class="hljs-variable">$num</span></span><span> * </span><span><span class="hljs-variable">$num</span></span><span>, </span><span><span class="hljs-variable">$nums</span></span><span>);

</span><span><span class="hljs-title function_ invoke__">print_r</span></span><span>(</span><span><span class="hljs-variable">$squared</span></span><span>);  </span><span><span class="hljs-comment">// 輸出 [1, 4, 9, 16]</span></span><span>
</span></span>

3. 使用strval和array_map轉換數組元素類型

假設我們有一個包含多種數據類型（如整數、浮點數、布爾值等）的數組，而我們需要將所有元素統一轉換為字符串。我們可以利用array_map函數和strval函數來實現這一點。

下面是一個例子，展示如何將一個混合類型的數組轉換為字符串數組：

 <span><span><span class="hljs-variable">$inputArray</span></span><span> = [</span><span><span class="hljs-number">123</span></span><span>, </span><span><span class="hljs-number">3.14</span></span><span>, </span><span><span class="hljs-literal">true</span></span><span>, </span><span><span class="hljs-literal">false</span></span><span>, </span><span><span class="hljs-literal">null</span></span><span>, </span><span><span class="hljs-string">"hello"</span></span><span>];

</span><span><span class="hljs-variable">$outputArray</span></span><span> = </span><span><span class="hljs-title function_ invoke__">array_map</span></span><span>(</span><span><span class="hljs-string">'strval'</span></span><span>, </span><span><span class="hljs-variable">$inputArray</span></span><span>);

</span><span><span class="hljs-title function_ invoke__">print_r</span></span><span>(</span><span><span class="hljs-variable">$outputArray</span></span><span>);
</span></span>

輸出：

 <span><span><span class="hljs-title function_ invoke__">Array</span></span><span>
(
    [</span><span><span class="hljs-number">0</span></span><span>] =&gt; </span><span><span class="hljs-number">123</span></span><span>
    [</span><span><span class="hljs-number">1</span></span><span>] =&gt; </span><span><span class="hljs-number">3.14</span></span><span>
    [</span><span><span class="hljs-number">2</span></span><span>] =&gt; </span><span><span class="hljs-number">1</span></span><span>
    [</span><span><span class="hljs-number">3</span></span><span>] =&gt; 
    [</span><span><span class="hljs-number">4</span></span><span>] =&gt; 
    [</span><span><span class="hljs-number">5</span></span><span>] =&gt; hello
)
</span></span>

如上所示， array_map會將strval應用到數組中的每個元素，最終返回一個新的數組，其中所有元素都已轉換為字符串。

4. 優化使用array_map和strval

在某些情況下，我們可能會想要對數組中的元素進行更多的預處理，比如過濾掉null或false值。在這種情況下，可以先用array_filter函數過濾數組，然後再用array_map和strval來轉換類型。

例如，我們可以先過濾掉所有為null和false的值，再將其轉換為字符串：

 <span><span><span class="hljs-variable">$inputArray</span></span><span> = [</span><span><span class="hljs-number">123</span></span><span>, </span><span><span class="hljs-number">3.14</span></span><span>, </span><span><span class="hljs-literal">true</span></span><span>, </span><span><span class="hljs-literal">false</span></span><span>, </span><span><span class="hljs-literal">null</span></span><span>, </span><span><span class="hljs-string">"hello"</span></span><span>, </span><span><span class="hljs-number">0</span></span><span>, </span><span><span class="hljs-string">"world"</span></span><span>];

</span><span><span class="hljs-variable">$filteredArray</span></span><span> = </span><span><span class="hljs-title function_ invoke__">array_filter</span></span><span>(</span><span><span class="hljs-variable">$inputArray</span></span><span>, fn(</span><span><span class="hljs-variable">$value</span></span><span>) =&gt; </span><span><span class="hljs-variable">$value</span></span><span> !== </span><span><span class="hljs-literal">false</span></span><span> &amp;&amp; </span><span><span class="hljs-variable">$value</span></span><span> !== </span><span><span class="hljs-literal">null</span></span><span>);
</span><span><span class="hljs-variable">$outputArray</span></span><span> = </span><span><span class="hljs-title function_ invoke__">array_map</span></span><span>(</span><span><span class="hljs-string">'strval'</span></span><span>, </span><span><span class="hljs-variable">$filteredArray</span></span><span>);

</span><span><span class="hljs-title function_ invoke__">print_r</span></span><span>(</span><span><span class="hljs-variable">$outputArray</span></span><span>);
</span></span>

輸出：

 <span><span><span class="hljs-title function_ invoke__">Array</span></span><span>
(
    [</span><span><span class="hljs-number">0</span></span><span>] =&gt; </span><span><span class="hljs-number">123</span></span><span>
    [</span><span><span class="hljs-number">1</span></span><span>] =&gt; </span><span><span class="hljs-number">3.14</span></span><span>
    [</span><span><span class="hljs-number">2</span></span><span>] =&gt; </span><span><span class="hljs-number">1</span></span><span>
    [</span><span><span class="hljs-number">5</span></span><span>] =&gt; hello
    [</span><span><span class="hljs-number">7</span></span><span>] =&gt; world
)
</span></span>

通過這種方式，我們能更靈活地控制數組轉換的結果。

5. 總結

通過結合使用strval和array_map函數，我們能夠高效地將數組中的所有元素轉換為字符串。無論數組包含何種類型的數據， strval都能保證將每個元素以字符串形式返回。而藉助array_map ，我們能夠以簡潔的代碼同時操作整個數組，確保所有元素都經過一致的處理。對於復雜的數組預處理，我們還可以配合array_filter等函數進一步優化轉換過程。

相關標籤:
array_map