lappend manual page - Built-In Commands

## Tcl8.6.1/Tk8.6.1 Documentation > Tcl Commands, version 8.6.1 > lappend

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### NAME

lappend — Append list elements onto a variable

### SYNOPSIS

lappend varName ?value value value ...?

### DESCRIPTION

This command treats the variable given by varName as a list and appends each of the value arguments to that list as a separate element, with spaces between elements. If varName does not exist, it is created as a list with elements given by the value arguments. Lappend is similar to append except that the values are appended as list elements rather than raw text. This command provides a relatively efficient way to build up large lists. For example, “lappend a $b” is much more efficient than “set a [concat $a [list $b]]” when $a is long.

### EXAMPLE

Using lappend to build up a list of numbers.

    % set var 1
    1
    % lappend var 2
    1 2
    % lappend var 3 4 5
    1 2 3 4 5

### SEE ALSO

list, lindex, linsert, llength, lset, lsort, lrange

### KEYWORDS

append, element, list, variable
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