PadRight
PadRight[list, n] pads a list to length n with zeros on the right. PadRight[list, n, x] uses element x for padding.
Examples
Pad lists on the right:
PadRight[{1, 2, 3}, 6]
(* {1, 2, 3, 0, 0, 0} *)
PadRight[{a, b}, 5, "*"]
(* {a, b, "*", "*", "*"} *)
(* Make all sublists same length *)
lists = {{1}, {1, 2}, {1, 2, 3}}
PadRight[#, 4] & /@ lists
(* {{1, 0, 0, 0}, {1, 2, 0, 0}, {1, 2, 3, 0}} *)Please visit the official Wolfram Language Reference for more details.