php count_chars 返回字符串所用字符的信息

count_chars — 返回字符串所用字符的信息

count_chars函数基本语法

count_chars(string,mode)

统计 string 中每个字节值（0..255）出现的次数，使用多种模式返回结果。

count_chars参数介绍

参数	描述
string	必需。需要统计的字符串。
mode	可选。规定返回模式。默认是 0。以下是不同的返回模式： 0 - 数组，ASCII 值为键名，出现的次数为键值 1 - 数组，ASCII 值为键名，出现的次数为键值，只列出出现次数大于 0 的值 2 - 数组，ASCII 值为键名，出现的次数为键值，只列出出现次数等于 0 的值 3 - 字符串，带有所有使用过的不同的字符 4 - 字符串，带有所有未使用过的不同的字符

count_chars返回值

根据不同的 mode， count_chars() 返回下列不同的结果：

• 0 - 以所有的每个字节值作为键名，出现次数作为值的数组。
• 1 - 与 0 相同，但只列出出现次数大于零的字节值。
• 2 - 与 0 相同，但只列出出现次数等于零的字节值。
• 3 - 返回由所有使用了的字节值组成的字符串。
• 4 - 返回由所有未使用的字节值组成的字符串。      

count_chars实例

<?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.<br/>" ;
}
?> 

在线运行

运行结果：

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.