如何运用PHP函数count()求出数组的长度
- WBOYOriginal
- 2016-06-13 11:06:39801browse
新学int count ( mixed var)
返回 var 中的单元数目，通常是一个 array（任何其它类型都只有一个单元）。
如果 var 不是数组类型，将返回 1（例外：count(NULL) 的结果是 0）。
警告
PHP函数count()对没有初始化的变量返回 0，但对于空的数组也会返回 0。用 isset() 来测试变量是否已经初始化。
例子 1. count() 例子
<ol class="dp-xml">
<li class="alt"><span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">php</span></font></strong><span> </span></span></li>
<li class=""><span>$vegetables[0] = "corn"; </span></li>
<li class="alt"><span>$vegetables[1] = "broccoli"; </span></li>
<li class=""><span>$vegetables[2] = "zucchini"; </span></li>
<li class="alt">
<span>$</span><span class="attribute"><font color="#ff0000">text</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">implode</font></span><span>(",", $vegetables); </span>
</li>
<li class=""><span>echo $text; </span></li>
<li class="alt">
<span></span><span class="tag"><strong><font color="#006699">?></font></strong></span><span> </span><span></span>
</li>
</ol>
有时如果不知道PHP函数count()的话，使用笨方法：select count（*）from table
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