實例
傳回一個字串，包含所有在"Hello World!" 中使用過的不同字元（模式3）：
<?php $str = "Hello World!"; echo count_chars($str,3); ?>
定義和用法
count_chars() 函數傳回字串所用字元的資訊（例如，ASCII 字元在字串中出現的次數，或某個字元是否已經在字串中使用過）。
文法
count_chars(string,mode)
參數 說明
#string 規定要檢查的字串。
mode 選擇。規定返回模式。預設是 0。有以下不同的回傳模式：
0 - 陣列# # 1 - 數組，ASCII 值為鍵名，出現的次數為鍵值，只列出出現次數大於0 的值
2 - 陣列，ASCII 值為鍵名，出現時的次數為鍵值，## 3 - 字串，並使用所有使用過的不同的字元
# # 帶有所有未使用過的不同的字元技術細節傳回值： 取決於指定的 mode 參數。 PHP 版本： 4+ 更多實例實例1傳回字串，包含所有在"Hello World!" 中未使用過的字元（模式4）：<?php $str = "Hello World!"; echo count_chars($str,4); ?>
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>'".chr($key)."'</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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