常量 · PHP学习 · 看云

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# 常量定义： ``` <pre class="calibre10">``` <span class="token4">define</span><span class="token3">(</span><span class="token2">'IN_DISCUZ'</span><span class="token3">,</span> TRUE<span class="token3">)</span><span class="token3">;</span> ``` ``` 校验是否定义： ``` <pre class="calibre10">``` <span class="token5">if</span><span class="token3">(</span><span class="token1">!</span><span class="token4">defined</span><span class="token3">(</span><span class="token2">'IN_DISCUZ'</span><span class="token3">)</span><span class="token3">)</span> <span class="token3">{</span> <span class="token4">exit</span><span class="token3">(</span><span class="token2">'Access Denied'</span><span class="token3">)</span><span class="token3">;</span> <span class="token3">}</span> ``` ``` 需要记住的的系统常量 ``` <pre class="calibre17">``` PHP_EOL<span class="token">//换行适合在命令端浏览器适合br </span> DIRECTORY_SEPARATOR<span class="token">//路径分隔符，目录分隔符</span> ``` ```