count_chars

(PHP 4, PHP 5, PHP 7)

count_chars - 返回有关字符串中使用的字符的信息

描述

mixed count_chars ( string $string [, int $mode = 0 ] )

计算字符串中每个字节值（0..255）的出现次数，并以各种方式返回它。

参数

string

被检查的字符串。

mode

查看返回值。

返回值

根据mode count_chars（）返回以下值之一：

0 - 一个数组，其中字节值为键，每个字节的频率为值。

1 - 与0相同，但仅列出频率大于零的字节值。

2 - 与0相同，但仅列出频率等于零的字节值。

3 - 返回包含所有唯一字符的字符串。

4 - 返回包含所有未使用字符的字符串。

例子

示例＃1 count_chars（）示例

<?php
$data = "Two Ts and one F.";

foreach (count_chars($data, 1) as $i => $val) {
   echo "There were $val instance(s) of \"" , chr($i) , "\" in the string.\n";
}
?>

上面的例子将输出：

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.

扩展内容

strpos（） - 查找字符串中第一次出现子字符串的位置

substr_count（） - 计算子串出现次数

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