php返回字符串所有信息的函数count_chars()

实例

返回一个字符串，包含所有在 "Hello World!" 中使用过的不同字符（模式 3）：

<?php
$str = "Hello World!";
echo count_chars($str,3);
?>

定义和用法

count_chars() 函数返回字符串所用字符的信息（例如，ASCII 字符在字符串中出现的次数，或者某个字符是否已经在字符串中使用过）。

语法

count_chars(string,mode)

参数                       描述

string                     必需。规定要检查的字符串。    

mode                      可选。规定返回模式。默认是 0。有以下不同的返回模式：

                               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

技术细节

返回值：       取决于指定的 mode 参数。    

PHP 版本：   4+    

更多实例

实例 1

返回一个字符串，包含所有在 "Hello World!" 中未使用过的字符（模式 4）：

<?php
$str = "Hello World!";
echo count_chars($str,4);
?>

实例 2

在本实例中，我们将使用 count_chars() 来检查字符串，返回模式设置为 1。模式 1 将返回一个数组，ASCII 值为键名，出现的次数为键值：

<?php
$str = "Hello World!";
print_r(count_chars($str,1));
?>

实例 3

统计 ASCII 字符在字符串中出现的次数另一个实例：

<?php
$str = "PHP is pretty fun!!";
$strArray = count_chars($str,1);

foreach ($strArray as $key=>$value)
{
echo "The character <b>&#39;".chr($key)."&#39;</b> was found $value time(s)<br>";
}
?>

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/>" ;
}
?>

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.

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