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English
<span><span><span class="hljs-meta"><?php</span></span><span>
</span><span><span class="hljs-comment">// This is a pre-code block unrelated to the main article content</span></span><span>
</span><span><span class="hljs-function"><span class="hljs-keyword">function</span></span></span><span> </span><span><span class="hljs-title">dummyFunction</span></span><span>(</span><span><span class="hljs-params"></span></span><span>) {
</span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-string">"This code is unrelated to the article content and is only for demonstration"</span></span><span>;
}
</span><span><span class="hljs-meta">?></span></span><span>
<p><hr></p>
<p></span><?php<br>
/*</p>
<ul>
<li>
<p>Title: How to Fix Infinite Loop When Using strval on an Object</p>
</li>
<li></li>
<li>
<p>In PHP, the strval() function is used to convert a variable to a string. When an object is passed in,</p>
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<p>if that object implements the __toString() magic method, strval() will call that method and return its string.</p>
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<li></li>
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<p>However, if the internal logic of the object is poorly designed, such as calling strval() either directly or indirectly</p>
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<p>within the __toString() method (or calling __toString() again), it can lead to an infinite loop, which may crash the program</p>
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<p>or cause memory overflow.</p>
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<li></li>
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<p>This article explains why the infinite loop happens and provides common solutions.<br>
*/</p>
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</ul>
<p>class Example {<br>
public $value;</p>
</span><span><span class="hljs-variable language_">$this</span></span><span>->value = </span><span><span class="hljs-variable">$value</span></span><span>;
}
</span><span><span class="hljs-keyword">public</span></span><span> </span><span><span class="hljs-function"><span class="hljs-keyword">function</span></span></span><span> </span><span><span class="hljs-title">__toString</span></span><span>(</span><span><span class="hljs-params"></span></span><span>) {
</span><span><span class="hljs-comment">// Incorrect example: calling strval($this) here causes infinite loop</span></span><span>
</span><span><span class="hljs-comment">// return strval($this);</span></span><span>
</span><span><span class="hljs-comment">// Correct approach: return a string representation</span></span><span>
</span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-string">"Example value: "</span></span><span> . </span><span><span class="hljs-variable language_">$this</span></span><span>->value;
}
}
$obj = new Example("Hello World");
// Calling strval() directly will trigger toString()
echo strval($obj) . PHP_EOL;
/*
Why does infinite recursion occur?
When __toString() calls strval($this), PHP will call __toString() again,
creating a recursive loop.
Solutions:
Avoid any code in __toString() that would trigger another __toString() call, such as strval($this).
Simply return a string value and don’t rely on converting the object itself.
If the object contains complex structures, avoid accessing those that may cause indirect conversions during string conversion.
Another scenario is when an object’s property is a reference to the object itself, leading to circular references.
In this case, serialization or string conversion may also fall into an infinite loop. A good fix is to design
a clear data structure or implement safeguards against circular references.
*/
/*
Summary:
When using strval() on an object, ensure the __toString() method does not call strval($this) directly or indirectly.
Keep the __toString() method simple—just return a string.
Design your objects carefully to avoid circular references that may cause recursion during serialization or conversion.
*/
