(PHP 4, PHP 5, PHP 7)
count_chars — 返回字符串所用字符的信息
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。
string需要统计的字符串。
mode参见返回的值。
根据不同的 mode，count_chars()
返回下列不同的结果：
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.