关于php正则表达式的两点备注

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
　　
　　/\*.*?\*/