lsearch

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



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NAME
       lsearch - See if a list contains a particular element

SYNOPSIS
       lsearch ?options? list pattern
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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 or (if options -all or -inline are specified) the
       empty string.  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
              specified, 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 specified.

   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
              interpretation 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
              comparisons (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
       precedence.  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
              element 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 complete
              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}

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



Tcl                                    8.6                            lsearch(n)