php：count_chars 用法

函数结构

函数名	返回值类型	描述
count_chars	mixed	返回字符串所用字符的信息
参数名	数据类型	是否必须	备注
$string	string	必须	字符串
$mode	int	可空默认值:0	整数型

函数原型

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

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。

参数

string: 需要统计的字符串。
mode: 参见返回的值。

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。

范例

Example #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" ;
}
?>

以上例程会输出：

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.

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同类函数:

函数名	函数简介
addcslashes	以 C 语言风格使用反斜线转义字符串中的字符
addslashes	使用反斜线引用字符串
bin2hex	函数把ASCII字符的字符串转换为十六进制值
chop	rtrim 的别名
chr	返回指定的字符
chunk_split	将字符串分割成小块
convert_cyr_string	将字符由一种 Cyrillic 字符转换成另一种
convert_uudecode	解码一个 uuencode 编码的字符串
convert_uuencode	使用 uuencode 编码一个字符串
count_chars	返回字符串所用字符的信息
crc32	计算一个字符串的 crc32 多项式
crypt	单向字符串散列
echo	输出一个或多个字符串
explode	使用一个字符串分割另一个字符串
fprintf	将格式化后的字符串写入到流