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lindex(3tcl) Tcl Built-In Commands lindex(3tcl)
 


NAME

lindex - Retrieve an element from a list

SYNOPSIS

lindex list ?index...?



 


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 consecutively 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 arithmetic 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(3tcl), lappend(3tcl), linsert(3tcl), llength(3tcl), lsearch(3tcl),
  lset(3tcl), lsort(3tcl), lrange(3tcl), lreplace(3tcl), string(3tcl)



KEYWORDS

element, index, list



  

    8.4
    Tcl