count_chars
(PHP 4, PHP 5)
count_chars — 返回字符串所用字符的信息
说明
mixed count_chars ( string $string [, int $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。可选参数 mode 默认值为 0。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。
Example #1 count_chars() 示例 以上例程会输出：
<?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.
";
}
?>
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.
参见 strpos() 和 substr_count()。
