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man pages section 1: User Commands

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Updated: Thursday, June 13, 2019
 
 

lsearch (1t)

Name

lsearch - See if a list contains a particular element

Synopsis

lsearch ?options? list pattern

Description

lsearch(1t)                  Tcl Built-In Commands                 lsearch(1t)



______________________________________________________________________________

NAME
       lsearch - See if a list contains a particular element

SYNOPSIS
       lsearch ?options? list pattern
______________________________________________________________________________

DESCRIPTION
       This  command  searches  the  elements  of  list  to see if one of them
       matches pattern.  If so, the command returns the  index  of  the  first
       matching  element  (unless  the options -all or -inline are specified.)
       If not, the command returns -1.  The option arguments indicates how the
       elements  of  the  list are to be matched against pattern and must have
       one of the values below:

   MATCHING STYLE OPTIONS
       If all matching style options are omitted, the default  matching  style
       is  -glob.   If  more  than  one  matching style is specified, the last
       matching style given takes precedence.

       -exact Pattern is a literal string that is compared for exact  equality
              against each list element.

       -glob  Pattern  is  a  glob-style pattern which is matched against each
              list element using the same rules as the string match command.

       -regexp
              Pattern is treated as a regular expression and  matched  against
              each  list  element  using  the rules described in the re_syntax
              reference page.

       -sorted
              The list elements are in sorted order.  If this option is speci-
              fied,  lsearch  will use a more efficient searching algorithm to
              search list.  If no other options are specified, list is assumed
              to  be sorted in increasing order, and to contain ASCII strings.
              This option is mutually exclusive with -glob and -regexp, and is
              treated  exactly like -exact when either -all or -not are speci-
              fied.

   GENERAL MODIFIER OPTIONS
       These options may be given with all matching styles.

       -all   Changes the result to be the list of all  matching  indices  (or
              all matching values if -inline is specified as well.) If indices
              are returned, the indices will be in numeric  order.  If  values
              are returned, the order of the values will be the order of those
              values within the input list.

       -inline
              The matching value is returned instead of its index (or an empty
              string  if  no  value matches.)  If -all is also specified, then
              the result of the  command  is  the  list  of  all  values  that
              matched.

       -not   This  negates the sense of the match, returning the index of the
              first non-matching value in the list.

       -start index
              The list is searched starting at position index.  The  interpre-
              tation  of the index value is the same as for the command string
              index, supporting simple index arithmetic and  indices  relative
              to the end of the list.

   CONTENTS DESCRIPTION OPTIONS
       These  options  describe  how  to interpret the items in the list being
       searched.  They are only meaningful  when  used  with  the  -exact  and
       -sorted  options.   If  more  than one is specified, the last one takes
       precedence.  The default is -ascii.

       -ascii The list elements are to be examined  as  Unicode  strings  (the
              name is for backward-compatibility reasons.)

       -dictionary
              The list elements are to be compared using dictionary-style com-
              parisons (see lsort for a fuller description).  Note  that  this
              only  makes  a meaningful difference from the -ascii option when
              the -sorted option is given, because values are only dictionary-
              equal when exactly equal.

       -integer
              The list elements are to be compared as integers.

       -nocase
              Causes  comparisons  to be handled in a case-insensitive manner.
              Has no effect if combined with  the  -dictionary,  -integer,  or
              -real options.

       -real  The list elements are to be compared as floating-point values.

   SORTED LIST OPTIONS
       These options (only meaningful with the -sorted option) specify how the
       list is sorted.  If more than one is given, the last one  takes  prece-
       dence.  The default option is -increasing.

       -decreasing
              The  list  elements are sorted in decreasing order.  This option
              is only meaningful when used with -sorted.

       -increasing
              The list elements are sorted in increasing order.   This  option
              is only meaningful when used with -sorted.

       -bisect
              Inexact  search  when the list elements are in sorted order. For |
              an increasing list the last index where the element is less than |
              or  equal  to the pattern is returned. For a decreasing list the |
              last index where the element is greater than  or  equal  to  the |
              pattern  is returned. If the pattern is before the first element |
              or the list is empty,  -1  is  returned.   This  option  implies |
              -sorted and cannot be used with either -all or -not.

   NESTED LIST OPTIONS
       These options are used to search lists of lists.  They may be used with
       any other options.

       -index indexList
              This option is designed for use  when  searching  within  nested
              lists.   The indexList argument gives a path of indices (much as
              might be used with the lindex or lset commands) within each ele-
              ment to allow the location of the term being matched against.

       -subindices
              If  this option is given, the index result from this command (or
              every index result when -all is also specified) will be  a  com-
              plete  path  (suitable  for  use with lindex or lset) within the
              overall list to the term  found.   This  option  has  no  effect
              unless  the  -index is also specified, and is just a convenience
              short-cut.

EXAMPLES
       Basic searching:

              lsearch {a b c d e} c
                    -> 2
              lsearch -all {a b c a b c} c
                    -> 2 5

       Using lsearch to filter lists:

              lsearch -inline {a20 b35 c47} b*
                    -> b35
              lsearch -inline -not {a20 b35 c47} b*
                    -> a20
              lsearch -all -inline -not {a20 b35 c47} b*
                    -> a20 c47
              lsearch -all -not {a20 b35 c47} b*
                    -> 0 2

       This can even do a "set-like" removal operation:

              lsearch -all -inline -not -exact {a b c a d e a f g a} a
                    -> b c d e f g

       Searching may start part-way through the list:

              lsearch -start 3 {a b c a b c} c
                    -> 5

       It is also possible to search inside elements:

              lsearch -index 1 -all -inline {{a abc} {b bcd} {c cde}} *bc*
                    -> {a abc} {b bcd}


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+------------------+
       |ATTRIBUTE TYPE | ATTRIBUTE VALUE  |
       +---------------+------------------+
       |Availability   | runtime/tcl-8    |
       +---------------+------------------+
       |Stability      | Uncommitted      |
       +---------------+------------------+
SEE ALSO
       foreach(n), list(n),  lappend(n),  lindex(n),  linsert(n),  llength(n),
       lset(n), lsort(n), lrange(n), lreplace(n), string(n)

KEYWORDS
       binary search, linear search, list, match, pattern, regular expression,
       search, string



NOTES
       This    software    was    built    from    source     available     at
       https://github.com/oracle/solaris-userland.    The  original  community
       source was downloaded from  http://prdownloads.sourceforge.net/tcl/tcl-
       core8.6.7-src.tar.gz

       Further information about this software can be found on the open source
       community website at https://www.tcl.tk/.



Tcl                                   8.6                          lsearch(1t)