正则severaltipsaboutRegularExpressions
1.processfor"greedy"
Bydefault,thequantifiersare"greedy",thatis,they
matchasmuchaspossible(uptothemaximumnumberofper-
mittedtimes),withoutcausingtherestofthepatternto
fail.Theclassicexampleofwherethisgivesproblemsisin
tryingtomatchcommentsinCprograms.Theseappearbetween
thesequences/*and*/andwithinthesequence,individual
*and/charactersmayappear.AnattempttomatchCcom-
mentsbyapplyingthepattern
/\*.*\*/
tothestring
/*firstcommand*/notcomment/*secondcomment*/
fails,becauseitmatchestheentirestringduetothe
greedinessofthe.*item.
However,ifaquantifierisfollowedbyaquestionmark,
thenitceasestobegreedy,andinsteadmatchestheminimum
numberoftimespossible,sothepattern
/\*.*?\*/
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