返回子字符串在字符串中第一次出现的位置； 看帮助：function Pos(Substr: string; S: string): Integer;DescriptionPos searches for a substring, Substr, in a string, S. Substr and S are string-type expressions.Pos searches for Substr within S and returns an integer value that is the index of the first character of Substr within S. Pos is case-sensitive. If Substr is not found, Pos returns zero.
看帮助：function Pos(Substr: string; S: string): Integer;DescriptionPos searches for a substring, Substr, in a string, S. Substr and S are string-type expressions.Pos searches for Substr within S and returns an integer value that is the index of the first character of Substr within S. Pos is case-sensitive. If Substr is not found, Pos returns zero.