When overridden in a derived class, calculates the number of bytes produced by encoding a set of characters starting at the specified characterpointer.
在衍生类别中覆写时，计算从指定的字元指标开始，编码一组字元所产生的位元组数目。
2
When overridden in a derived class, encodes a set of characters starting at the specified characterpointer into a sequence of bytes that are stored starting at the specified byte pointer.
Normal control characters (characters with values less than 32) : This especially includes character 0, traditionally called NUL; I call it NIL to distinguish it from c's NULL pointer.