clears all values, definitions, attributes, defaults, options and messages for the symbols si.
clears all symbols whose names textually match any of the arbitrary string patterns patti.
clears any symbols that are equal to or whose names match any of the speci.
- The pattern patt can be given as a string with metacharacters, as StringExpression[…] or as RegularExpression["regex"]. »
- ClearAll allows abbreviated string patterns containing the following metacharacters:
* zero or more characters @ one or more characters, excluding uppercase letters
- ClearAll["context`*"] clears all symbols in a particular context. »
- ClearAll["`*"] clears all symbols in the current context. »
- ClearAll does not affect symbols with the attributes Locked or Protected. »
- ClearAll has attribute HoldAll. »
Examplesopen allclose all
Symbol Inputs (11)
Using Patterns (5)
Specify symbols to clear as string patterns:
Clear all symbols in the current context:
Clear all symbols in a given context:
Clear all 2-character symbols in the current context using StringExpression:
The symbols x1 and x2 were cleared, but y remains unaffected:
Clear all 3-character symbols in the current context using RegularExpression:
Properties & Relations (6)
ClearAll[pattern] clears the same symbols as ClearAll/@Names[pattern]:
Clear does not remove attributes, defaults or options:
Use ClearAll to clear everything:
Clear does not remove messages:
Use ClearAll to clear messages:
ClearAll removes all properties and definitions but leaves the symbol intact:
Remove removes the symbol completely:
Use Unset (=.) to clear definitions with a particular left-hand side:
Clear all definitions and properties:
ClearAll has the attribute HoldAll:
Possible Issues (3)
Protected symbols cannot be cleared:
Use Unprotect to clear definitions of protected symbols:
Clear can clear the values and definitions for locked symbols:
ClearAll does not affect locked symbols:
When using a pattern without a context mark, all matching symbols on $ContextPath are cleared:
The symbol xy was cleared, along with attempts to clear several system symbols:
Use a pattern with an explicit context mark avoid potentially matching symbols from system or other contexts:
Wolfram Research (1988), ClearAll, Wolfram Language function, https://reference.wolfram.com/language/ref/ClearAll.html (updated 2022).
Wolfram Language. 1988. "ClearAll." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2022. https://reference.wolfram.com/language/ref/ClearAll.html.
Wolfram Language. (1988). ClearAll. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/ClearAll.html