lindex(n) Tcl Built-In Commands lindex(n)
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NAME
lindex - Retrieve an element from a list
SYNOPSIS
lindex list ?index...?
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DESCRIPTION
The lindex command accepts a parameter, list, which it treats as a Tcl list. It also
accepts zero or more indices into the list. The indices may be presented either consecu-
tively on the command line, or grouped in a Tcl list and presented as a single argument.
If no indices are presented, the command takes the form:
lindex list
or
lindex list {}
In this case, the return value of lindex is simply the value of the list parameter.
When presented with a single index, the lindex command treats list as a Tcl list and
returns the index'th element from it (0 refers to the first element of the list). In
extracting the element, lindex observes the same rules concerning braces and quotes and
backslashes as the Tcl command interpreter; however, variable substitution and command
substitution do not occur. If index is negative or greater than or equal to the number of
elements in value, then an empty string is returned. The interpretation of each simple |
index value is the same as for the command string index, supporting simple index arith- |
metic and indices relative to the end of the list.
If additional index arguments are supplied, then each argument is used in turn to select
an element from the previous indexing operation, allowing the script to select elements
from sublists. The command,
lindex $a 1 2 3
or
lindex $a {1 2 3}
is synonymous with
lindex [lindex [lindex $a 1] 2] 3
EXAMPLES
lindex {a b c}
-> a b c
lindex {a b c} {}
-> a b c
lindex {a b c} 0
-> a
lindex {a b c} 2
-> c
lindex {a b c} end
-> c
lindex {a b c} end-1
-> b
lindex {{a b c} {d e f} {g h i}} 2 1
-> h
lindex {{a b c} {d e f} {g h i}} {2 1}
-> h
lindex {{{a b} {c d}} {{e f} {g h}}} 1 1 0
-> g
lindex {{{a b} {c d}} {{e f} {g h}}} {1 1 0}
-> g
SEE ALSO
list(n), lappend(n), linsert(n), llength(n), lsearch(n), lset(n), lsort(n), lrange(n),
lreplace(n), string(n) |
KEYWORDS
element, index, list
Tcl 8.4 lindex(n)
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