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







lindex - Retrieve an element from a list








lindex list ?index...?










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












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










list(n), lappend(n), linsert(n), llength(n), lsearch(n), lset(n),
    lsort(n), lrange(n), lreplace(n), string(n)










element, index, list







  

    8.4
    Tcl