Wolfram: Symbol Unset, Clear, Remove

By Xah Lee. Date: .

normally, you should just use Clear because that is the most simple.

Unset

Unset

Unset[pattern]

🔸 SHORT SYNTAX: pattern=. 

xx=3;
Print[xx]
(* 3 *)

Print[Unset[xx]]
(* Null *)

Print[xx]
(* xx *)
(* example of Unset using syntax shortcut *)

xx=3;
Print[xx]
(* 3 *)

Print[xx=.]
(* Null *)

Print[xx]
(* xx *)
(* example of Unset on a pattern that's not just a symbol *)

ff[0] = 3;
Print[ff[0]]
(* 3 *)

Print[ Unset[ff[0]] ]
(* Null *)

Print[ff[0]]
(* ff[0] *)

Clear a Symbol's Value

Clear[sym1, sym2, etc]

Clear the values and definitions of Symbols.

💡 TIP: advanced. Clear does not clear attributes, defaults, options or messages associated with symbols. 

xx = 3
(* 3 *)

yy = 4
(* 4 *)

{xx, yy}
(* {3, 4} *)

Clear[xx]

{xx, yy}
(* {xx, 4} *)
(* clear multiple variables *)
Clear[x1,x2]
(* clear all variable starting with x *)
Clear["x*"]
(* clear all symbols in current context *)
(* this is most useful for clearing all user-defined values in current session. *)
Names["`*"]

Clear Everything of a Symbol

ClearAll

ClearAll[symbol1, symbol2, etc]

Clear all values, definitions, attributes, defaults, options and messages.

Remove a symbol

Remove

Remove Symbols from the system.

💡 TIP: you basically never need to remove a symbol. Usually you just need Clear.