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

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.