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
← convert_uuencode
crc32 →
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