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>count_chars</H1
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><P
> (PHP 4, PHP 5)</P
>count_chars -- 返回字符串所用字符的信息</DIV
><DIV
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><H2
>说明</H2
>mixed <B
CLASS="methodname"
>count_chars</B
> ( string string [, int mode] )<BR
></BR
><P
> 统计 <CODE
CLASS="parameter"
>string</CODE
>
中每个字节值（0..255）出现的次数，使用多种模式返回结果。可选参数
<CODE
CLASS="parameter"
>mode</CODE
> 默认值为
0。根据不同的
<CODE
CLASS="parameter"
>mode</CODE
>，<B
CLASS="function"
>count_chars()</B
>
返回下列不同的结果：
<P
></P
><UL
><LI
><P
> 0 - 以所有的每个字节值作为键名，出现次数作为值的数组。
</P
></LI
><LI
><P
> 1 - 与 0 相同，但只列出出现次数大于零的字节值。
</P
></LI
><LI
><P
> 2 - 与 0 相同，但只列出出现次数等于零的字节值。
</P
></LI
><LI
><P
>
3 - 返回由所有使用了的字节值组成的字符串。
</P
></LI
><LI
><P
>
4 - 返回由所有未使用的字节值组成的字符串。
</P
></LI
></UL
>
</P
><P
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><B
>例 1. <B
CLASS="function"
>count_chars()</B
> 示例</B
></P
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><code><font color="#000000">
<font color="#0000BB"><?php<br />$data </font><font color="#007700">= </font><font color="#DD0000">"Two Ts and one F."</font><font color="#007700">;<br /><br />foreach (</font><font color="#0000BB">count_chars</font><font color="#007700">(</font><font color="#0000BB">$data</font><font color="#007700">, </font><font color="#0000BB">1</font><font color="#007700">) as </font><font color="#0000BB">$i </font><font color="#007700">=> </font><font color="#0000BB">$val</font><font color="#007700">) {<br /> echo </font><font color="#DD0000">"There were $val instance(s) of </font><font color="#007700">\"</font><font color="#DD0000">" </font><font color="#007700">, </font><font color="#0000BB">chr</font><font color="#007700">(</font><font color="#0000BB">$i</font><font color="#007700">) , </font><font color="#DD0000">"\" in the string.\n"</font><font color="#007700">;<br />}<br /></font><font color="#0000BB">?></font>
</font>
</code></TD
></TR
></TABLE
><P
>上例将输出：</P
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><PRE
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>There were 4 instance(s) of " " in the string.
There were 1 instance(s) of "." in the string.
There were 1 instance(s) of "F" in the string.
There were 2 instance(s) of "T" in the string.
There were 1 instance(s) of "a" in the string.
There were 1 instance(s) of "d" in the string.
There were 1 instance(s) of "e" in the string.
There were 2 instance(s) of "n" in the string.
There were 2 instance(s) of "o" in the string.
There were 1 instance(s) of "s" in the string.
There were 1 instance(s) of "w" in the string.</PRE
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>
</P
><P
> 参见 <A
HREF="function.strpos.html"
><B
CLASS="function"
>strpos()</B
></A
> 和
<A
HREF="function.substr-count.html"
><B
CLASS="function"
>substr_count()</B
></A
>。
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