perl ASCII码转换函数

chr

chr(65) is "A" in either ASCII or Unicode,and chr(0x263a) is a Unicode smiley face.

Negative values give the Unicode replacement character (chr(0xfffd)),except under the bytes pragma,where low eight bits of the value (truncated to an integer) are used.

If NUMBER is omitted,uses $_ .

For the reverse,use "ord".

Note that characters from 128 to 255 (inclusive) are by default internally not encoded as UTF-8 for backward compatibility reasons.