如果起始位置是正值，则它相对于字符串的开头；如果是负值，则是相对于字符串的末尾。

If the starting location is positive, it's relative to the beginning of the string; if it's negative, it's relative to the end of the string.

youdao

一种字符，由一个起始信号开头，一个或两个停止信号结尾。

A character including one start signal at the beginning and one or two stop signals at the end.

youdao

一种字符，由一个起始信号开头，一个或两个停止信号结尾。

A character including one start signal at the beginning and one or two stop signals at the end.

youdao