unset(n) Tcl Built-In Commands unset(n) 







unset - Delete variables








unset ?-nocomplain? ?--? ?name name name
    ...?










This command removes one or more variables. Each name is a
    variable name, specified in any of the ways acceptable to the set
    command. If a name refers to an element of an array then that element
    is removed without affecting the rest of the array. If a name
    consists of an array name with no parenthesized index, then the entire array
    is deleted. The unset command returns an empty string as result. If
    -nocomplain is specified as the first argument, any possible errors
    are suppressed. The option may not be abbreviated, in order to disambiguate
    it from possible variable names. The option -- indicates the end of
    the options, and should be used if you wish to remove a variable with the
    same name as any of the options. If an error occurs, any variables after the
    named one causing the error are not deleted. An error can occur when the
    named variable does not exist, or the name refers to an array element but
    the variable is a scalar, or the name refers to a variable in a non-existent
    namespace.








Create an array containing a mapping from some numbers to their
    squares and remove the array elements for non-prime numbers:




array set squares {


    1 1    6 36


    2 4    7 49


    3 9    8 64


    4 16   9 81


    5 25  10 100
}
puts "The squares are:"
parray squares
unset squares(1) squares(4) squares(6)
unset squares(8) squares(9) squares(10)
puts "The prime squares are:"
parray squares










set(n), trace(n), upvar(n)








remove, variable







  

    8.4
    Tcl