PHP 中的真假

php小編小新為您揭示PHP中的真假。 PHP作為一種流行的程式語言，常常被誤解或傳播假訊息。本文將從各種角度探討PHP中的真實情況，幫助讀者更了解這門語言的優缺點，避免被謠言誤導。讓我們一起來揭開PHP的真相吧！

使用 false 時，它不會顯示任何輸出。值得注意的是，瀏覽器總是以字串的形式呈現這些值。

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在 php 中使用 true 和 false 作為布林邏輯值

布林值是邏輯值。它們可以是真或假。

兩者在 php 中都是區分大小寫的，也是 php 中的簡單資料型別。

<code><code class="language-php hljs" data-lang="php"><span style="display:flex;"><span> <span style="color:#19177c">$true</span> <span style="color:#666">=</span> <span style="color:#008000;font-weight:bold">True</span>; <span style="color:#408080;font-style:italic">//returns 1 
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span> <span style="color:#19177c">$false</span> <span style="color:#666">=</span> <span style="color:#008000;font-weight:bold">False</span>; <span style="color:#408080;font-style:italic">// return nothing 
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span><span style="color:#008000;font-weight:bold">echo</span> <span style="color:#19177c">$true</span><span style="color:#666">.</span>PHP_EOL;
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">echo</span> <span style="color:#19177c">$false</span>;
</span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic">//using comparis<strong class="keylink">io</strong>n operator to check boolean values
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span><span style="color:#008000;font-weight:bold">if</span> (<span style="color:#19177c">$a</span> <span style="color:#666">==</span> <span style="color:#ba2121">"abc"</span>) {
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">echo</span> <span style="color:#ba2121">"return boolean value"</span>; <span style="color:#408080;font-style:italic">//returns nothing since $a is not equal to abc thus it is a false
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span> }
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">if</span> (<span style="color:#008000;font-weight:bold">TRUE</span>) {
</span></span><span style="display:flex;"><span>	<span style="color:#408080;font-style:italic">//because true means true
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span><span style="color:#008000;font-weight:bold">echo</span> <span style="color:#ba2121">"Your condition is executed!"</span><span style="color:#666">.</span>PHP_EOL; 
</span></span><span style="display:flex;"><span>}
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">if</span> (<span style="color:#008000;font-weight:bold">false</span>) {
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">echo</span> <span style="color:#ba2121">"It will print nothing"</span>; <span style="color:#408080;font-style:italic">//false returns nothing
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span> }
</span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic">//Determine integer comparisions with boolean values
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span><span style="color:#008000;font-weight:bold">echo</span> <span style="color:#666">5</span><span style="color:#666"><</span><span style="color:#666">10</span>; <span style="color:#408080;font-style:italic">//returns 1 since 5 is actually less ten (condition true)
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span><span style="color:#008000;font-weight:bold">echo</span> <span style="color:#666">10</span> <span style="color:#666">!=</span> <span style="color:#666">5</span>; <span style="color:#408080;font-style:italic">//returns 1 (true)
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span><span style="color:#008000;font-weight:bold">echo</span> <span style="color:#666">5</span> <span style="color:#666">==</span> <span style="color:#666">4</span>; <span style="color:#408080;font-style:italic">//false
</span></span></span></code></code>

#輸出：

<code><code class="language-text hljs" data-lang="text"><span style="display:flex;"><span>1 
</span></span><span style="display:flex;"><span>Your condition is executed!
</span></span><span style="display:flex;"><span>11
</span></span></code></code>

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在PHP 中使用var_dump() 函數決定布林值

我們也可以在php.ini 中轉換布林值。讓我們先了解這些參數的一些預定義值分配。

如果我們將以下值轉換為布林值，它們將被視為假：

• false 是 false。
• 0 也是 false。
• 諸如 0.0 和 -0.0 之類的浮點數也是 false。
• 具有 0 元素的陣列是 false。
• NULL 是 false。

相反，所有其他值都被認為是 true。

我們可以藉助轉儲布林值資訊的 var_dump() 函數來決定布林值。

讓我們用 var_dump 檢查上面提到的錯誤類型：

<code><code class="language-php hljs" data-lang="php"><span style="display:flex;"><span><span style="color:#666"><?</span>php
</span></span><span style="display:flex;"><span>var_dump((bool) <span style="color:#008000;font-weight:bold">false</span>);<span style="color:#408080;font-style:italic">//(false)
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span>var_dump((bool) <span style="color:#ba2121">"0"</span>); <span style="color:#408080;font-style:italic">//(false)
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span>var_dump((bool) <span style="color:#666">0.0</span>);<span style="color:#408080;font-style:italic">//(false)
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span>var_dump((bool) <span style="color:#666">-</span><span style="color:#666">0.0</span>);<span style="color:#408080;font-style:italic">//(false)
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span>var_dump((bool) <span style="color:#008000;font-weight:bold">NULL</span>); <span style="color:#408080;font-style:italic">//(false)
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span>var_dump((bool) <span style="color:#008000;font-weight:bold">array</span>()); <span style="color:#408080;font-style:italic">//(false)
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic">//true bools (a few examples)
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span>var_dump((bool)<span style="color:#008000;font-weight:bold">true</span>);<span style="color:#408080;font-style:italic">//true
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span>var_dump((bool)<span style="color:#666">1</span>);<span style="color:#408080;font-style:italic">//true
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span>var_dump((bool)<span style="color:#666">100</span>); <span style="color:#408080;font-style:italic">//true
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span>var_dump((bool) <span style="color:#008000;font-weight:bold">array</span>(<span style="color:#666">65</span>)); <span style="color:#408080;font-style:italic">//true
</span></span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic"></span><span style="color:#bc7a00">?></span><span >
</span></span></span></code></code>

輸出：

<code><code class="language-text hljs" data-lang="text"><span style="display:flex;"><span>bool(false)
</span></span><span style="display:flex;"><span>bool(false)
</span></span><span style="display:flex;"><span>bool(true)
</span></span><span style="display:flex;"><span>bool(false)
</span></span><span style="display:flex;"><span>bool(false)
</span></span><span style="display:flex;"><span>bool(false)
</span></span><span style="display:flex;"><span>bool(false)
</span></span><span style="display:flex;"><span>bool(true)
</span></span><span style="display:flex;"><span>bool(true)
</span></span><span style="display:flex;"><span>bool(true)
</span></span><span style="display:flex;"><span>bool(true)
</span></span></code></code>

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