Use var_dump() for detailed variable inspection and print_r() for quick readable output. 1. var_dump() shows type, size, and nested elements, ideal for APIs or uncertain data structures. 2. Wrap var_dump() in

 tags for readability and use it with multiple variables. 3. print_r() offers simplified structure view without types, suitable for CLI or quick checks. 4. Wrap print_r() in <pre class="brush:php;toolbar:false"> tags when used in HTML. 5. Choose var_dump() for type-related debugging and print_r() for cleaner logs. 6. Combine either with exit; to stop execution. Remove both before production deployment.<p><img src="/static/imghw/default1.png" data-src="https://img.php.cn/upload/article/000/000/000/175069751211039.jpg" class="lazy" alt="How do I use var_dump() or print_r() to inspect variables during debugging?"></p><p>When you're debugging PHP code, <code>var_dump()</code> and <code>print_r()</code> are two of the most commonly used tools to inspect variables. They help you see what’s inside a variable—its type, structure, and value—at a specific point in your script. Knowing how to use them effectively can save time when tracking down bugs or understanding data flow.</p><h3>Use <code>var_dump()</code> for detailed variable inspection</h3><p><code>var_dump()</code> is great when you want a full picture of a variable. It shows the type, size, and value of the variable. If it's an array or object, it will display all the nested elements too.</p><p>For example:</p><pre class='brush:php;toolbar:false;'>$data = ['name' => 'John', 'age' => 25];
var_dump($data);

You’ll get something like:

array(2) {
  ["name"]=>
  string(4) "John"
  ["age"]=>
  int(25)
}

This output tells you exactly what kind of data you're dealing with. That’s especially useful when handling user input or working with APIs where you’re not 100% sure what the structure looks like.

A few tips:

• Wrap var_dump() outputs with <pre class="brush:php;toolbar:false">&lt;/code&gt; tags if viewing in a browser, so it's easier to read.&lt;/li&gt;&lt;li&gt;Don’t forget that &lt;code&gt;var_dump()&lt;/code&gt; stops execution after printing, so place it strategically.&lt;/li&gt;&lt;li&gt;You can pass multiple variables into one &lt;code&gt;var_dump()&lt;/code&gt; call: &lt;code&gt;var_dump($a, $b);&lt;/code&gt;.&lt;/li&gt;&lt;/ul&gt;&lt;h3&gt;Use &lt;code&gt;print_r()&lt;/code&gt; for quick and readable output&lt;/h3&gt;&lt;p&gt;If you just need a quick look at arrays or objects without as much detail, &lt;code&gt;print_r()&lt;/code&gt; is more readable. It gives a simplified view and doesn't show types or lengths explicitly.&lt;/p&gt;&lt;p&gt;Example:&lt;/p&gt;&lt;pre class='brush:php;toolbar:false;'&gt;$data = ['name' =&gt; 'John', 'age' =&gt; 25]; print_r($data);</pre><p>Output:</p><pre class='brush:php;toolbar:false;'>Array ( [name] =&gt; John [age] =&gt; 25 )</pre><p>This format is often easier to scan quickly, especially for large arrays. And if you're working in a CLI environment (like running scripts from the terminal), <code>print_r() can be cleaner than var_dump().

  One thing to note:

  • When using print_r() in HTML, wrap it in <pre class="brush:php;toolbar:false">&lt;/code&gt; tags to preserve formatting: &lt;pre class='brush:php;toolbar:false;'&gt;echo '&lt;pre class=&quot;brush:php;toolbar:false&quot;&gt;'; print_r($data); echo '</pre>';</pre></li></ul><h3 id="Know-when-to-choose-one-over-the-other">Know when to choose one over the other</h3><p>Which one to use really depends on what you need:</p><ul><li><p>Use <code>var_dump() when:
    • You need to know exact data types.
    • You're troubleshooting type-related issues.
    • You want to see full details, including string length.

  • Use print_r() when:

    • You only care about values and structure.
    • You're doing a quick check during development.
    • You're logging output and don't need extra noise.

  Also, both functions can be combined with exit; or die(); to stop execution right after dumping the data. Like:

  var_dump($data); exit;

  That way, you avoid unnecessary output after the inspection point.

  Basically, these tools aren't fancy, but they're solid for everyday debugging. Just remember to remove or comment them out before pushing code live.

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