str_split(string $string, int $split_length = 1): array；
将一个字符串转换为数组。例：$characters = str_split($this->codeSet)
preg_split(string $pattern,string $subject, int $limit = -1, int $flags = 0
): array；通过一个正则表达式分隔给定字符串。例：$characters = preg_split('/(?<!^)(?!$)/u', $this->zhSet);
property_exists([mixed] $class, string $property): bool 检查对象或类是否具有该属性
