Provided by: tcl8.6-doc_8.6.1-4ubuntu1_all 
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. 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(3tcl), list(3tcl), lappend(3tcl), lindex(3tcl), linsert(3tcl), llength(3tcl),
lset(3tcl), lsort(3tcl), lrange(3tcl), lreplace(3tcl), string(3tcl)
KEYWORDS
binary search, linear search, list, match, pattern, regular expression, search, string