如何使用preg_match函數來驗證IP地址，保證格式正確且有效？

gitbox 2025-08-27

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如何使用preg_match函數來驗證IP地址，保證格式正確且有效？

在PHP中，`preg_match`函數是用來進行正則表達式匹配的一個非常強大的工具。當我們需要驗證用戶輸入的IP地址是否格式正確時，`preg_match`可以快速完成這項任務。本文將詳細講解如何使用它驗證IPv4和IPv6地址。

</span><span><span class="hljs-comment">### 1. IPv4地址驗證</span></span><span>

IPv4地址由四段數字組成，每段數字的範圍是</span><span><span class="hljs-number">0</span></span><span>到</span><span><span class="hljs-number">255</span></span><span>，中間用點號分隔，例如：</span><span><span class="hljs-number">192.168</span></span><span>.</span><span><span class="hljs-number">0.1</span></span><span>。為了確保格式和有效性，我們可以使用如下正則表達式：

```php
</span><span><span class="hljs-variable">$ipv4_pattern</span></span><span> = </span><span><span class="hljs-string">"/^((25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])\.){3}(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])$/"</span></span><span>;
</span><span><span class="hljs-variable">$ip</span></span><span> = </span><span><span class="hljs-string">"192.168.1.100"</span></span><span>;

</span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-title function_ invoke__">preg_match</span></span><span>(</span><span><span class="hljs-variable">$ipv4_pattern</span></span><span>, </span><span><span class="hljs-variable">$ip</span></span><span>)) {
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"IPv4地址格式正確"</span></span><span>;
} </span><span><span class="hljs-keyword">else</span></span><span> {
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"IPv4地址格式不正確"</span></span><span>;
}
</span></span>

解釋：

25[0-5]匹配250-255
2[0-4][0-9]匹配200-249
1[0-9]{2}匹配100-199
[1-9]?[0-9]匹配0-99
((...)\.){3}...確保有四段數字且中間用點分隔

2. IPv6地址驗證

IPv6地址格式更加複雜，由8組16進制數字組成，每組用冒號分隔。一個簡單的正則表達式示例如下：

 <span><span><span class="hljs-variable">$ipv6_pattern</span></span><span> = </span><span><span class="hljs-string">"/^([0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}$/"</span></span><span>;
</span><span><span class="hljs-variable">$ip</span></span><span> = </span><span><span class="hljs-string">"2001:0db8:85a3:0000:0000:8a2e:0370:7334"</span></span><span>;

</span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-title function_ invoke__">preg_match</span></span><span>(</span><span><span class="hljs-variable">$ipv6_pattern</span></span><span>, </span><span><span class="hljs-variable">$ip</span></span><span>)) {
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"IPv6地址格式正確"</span></span><span>;
} </span><span><span class="hljs-keyword">else</span></span><span> {
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"IPv6地址格式不正確"</span></span><span>;
}
</span></span>

3. 實用小技巧

如果你希望同時驗證IPv4和IPv6，可以使用filter_var函數，它內置了IP驗證功能：

 <span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-title function_ invoke__">filter_var</span></span><span>(</span><span><span class="hljs-variable">$ip</span></span><span>, FILTER_VALIDATE_IP)) {
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"IP地址有效"</span></span><span>;
} </span><span><span class="hljs-keyword">else</span></span><span> {
    </span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"IP地址無效"</span></span><span>;
}
</span></span>

在處理用戶輸入時，始終注意去除空格和無效字符，避免因前後空格導致匹配失敗：

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

對於大量IP地址的批量驗證，可以結合循環和preg_match ，高效檢查每一個輸入。

總結

使用preg_match結合精確的正則表達式，可以驗證IP地址格式是否正確且有效。對於IPv4，重點在於數字範圍和段數；對於IPv6，重點在於十六進制組和冒號分隔。掌握這些技巧，能夠讓你的PHP程序在處理網絡地址時更加安全和可靠。

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