1unset(n) Tcl Built-In Commands unset(n)
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8 unset - Delete variables
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11 unset ?-nocomplain? ?--? ?name name name ...?
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15 This command removes one or more variables. Each name is a variable
16 name, specified in any of the ways acceptable to the set command. If a
17 name refers to an element of an array then that element is removed
18 without affecting the rest of the array. If a name consists of an
19 array name with no parenthesized index, then the entire array is
20 deleted. The unset command returns an empty string as result. If
21 -nocomplain is specified as the first argument, any possible errors are
22 suppressed. The option may not be abbreviated, in order to disam‐
23 biguate it from possible variable names. The option -- indicates the
24 end of the options, and should be used if you wish to remove a variable
25 with the same name as any of the options. If an error occurs, any
26 variables after the named one causing the error are not deleted. An
27 error can occur when the named variable does not exist, or the name
28 refers to an array element but the variable is a scalar, or the name
29 refers to a variable in a non-existent namespace.
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32 Create an array containing a mapping from some numbers to their squares
33 and remove the array elements for non-prime numbers:
34 array set squares {
35 1 1 6 36
36 2 4 7 49
37 3 9 8 64
38 4 16 9 81
39 5 25 10 100
40 }
41 puts "The squares are:"
43 parray squares
44 unset [22msquares(1) squares(4) squares(6)
46 unset [22msquares(8) squares(9) squares(10)
47 puts "The prime squares are:"
49 parray squares
50
52 set(n), trace(n), upvar(n)
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55 remove, variable
56Tcl 8.4 unset(n)