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String matching: Difference between revisions
→{{header|Tcl}}: Another way to solve this
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set isSuffix [string equal $needle [string range $haystack end-[expr {[string length $needle]-1}] end]]</lang>
Of course, in the cases where the needle is a glob-safe string (i.e., doesn't have any of the characters “<tt>*?[\</tt>” in), this can be written far more conveniently:
<lang tcl>set isPrefix [string match $needle* $haystack]
set isContained [string match *$needle* $haystack]
set isSuffix [string match *$needle $haystack]</lang>
Another powerful technique is to use the regular expression engine in literal string mode:
<lang tcl>set isContained [regexp ***=$needle $haystack]</lang>
This can be extended by getting the <code>regexp</code> to return the locations of the matches, enabling the other forms of match to be done:
<lang tcl>set matchLocations [regexp -indices -all -inline ***=$needle $haystack]
# Each match location is a pair, being the index into the string where the needle started
# to match and the index where the needle finished matching
set isContained [expr {[llength $matchLocations] > 0}]
set isPrefix [expr {[lindex $matchLocations 0 0] == 0}]
set isSuffix [expr {[lindex $matchLocations end 1] == [string length $haystack]-1}]
set firstMatchStart [lindex $matchLocations 0 0]
puts "Found \"$needle\" in \"$haystack\" at $firstMatchStart"
foreach location $matchLocations {
puts "needle matched at index [lindex $location 0]"
}</lang>
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