3、取子串 A= How nice to see you B=substr(A, 5, 15) 4、字符串合并 a=How nice to see you B=Hello! World C=A+B3、取子串 A=‘How nice to see you!’ B=substr(A,5,15) 4、字符串合并 A=‘How nice to see you!’ B=‘Hello! World! C=A+B