unset manual page - Tcl Built-In Commands

## Tcl8.5.15/Tk8.5.15 Documentation > TclCmd > unset

### Tcl/Tk Applications | Tcl Commands | Tk Commands | Tcl Library | Tk Library

### NAME

unset - Delete variables

### SYNOPSIS

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

### DESCRIPTION

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.

### EXAMPLE

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

### SEE ALSO

set, trace, upvar

### KEYWORDS

remove, variable
Copyright © 1995-1997 Roger E. Critchlow Jr. Copyright © 1993 The Regents of the University of California. Copyright © 1994-1996 Sun Microsystems, Inc. Copyright © 2000 Ajuba Solutions.