Vector element can be referenced as sequence number in SPL

A1 Input a vector

A2 Get the third member of A1,return 6. The sequence number starts from 1 in SPL.

A3 Get the first 2 members of A1,return[1,2]

A4 Get the members from third to fifth,return [6,23,56]

A5 Get the members from third to last,return [6,23,56,1]

A6 Get the second member from the backward, return 56.

A7 Get the second and 4^thmembers from the backward,return [56,6]

A8 Get the members from the second to 4^thwith a sequence from backwards to forwards,return[56,23,6]