String的序数值是多少？ [关闭]

Question

I'm confused about the term Ordinal value of a character or a string in php documentation. Can somebody tell me what exactly an ordinal value is?

Answer 1

One "character" in PHP is one byte. Note that this is misleading for multi-byte characters, in which one character (say "漢") is encoded in multiple bytes. Anyway though, a byte is 8 bits and can represent a number between 0 and 255. The ordinal value of a character byte is simply this numerical value.

ord('a') -> 97

Read http://kunststube.net/encoding if you need more background information about bytes/characters/encodings.