c++ - regex("(abc|aa.*|bb.*)") Vs regex("(aa.*|bb.*|cc.*)"); -

-

this question has answer here:

i encounter weird problem when using regex in c++11 (ubuntu 14.4 ,gcc 4.8.2)

#include <iostream> #include <regex> using namespace std; int main() {     regex r("(abc|aa.*|bb.*)");     cout<<regex_match("bb11",r)<<endl;  //return false     cout<<regex_match("aa11",r)<<endl;  //return true     cout<<regex_match("abc",r)<<endl;   //return true     return 0; }

while

int main() {     regex r("(aa.*|bb.*|cc.*)");     cout<<regex_match("bb11",r)<<endl;  //return true     cout<<regex_match("aa11",r)<<endl;  //return true     cout<<regex_match("abc",r)<<endl;   //return false     return 0; }

i wondering why "bb11" got different result?

std::regex not supported in gcc until 4.9.

in 4.8.2 you'll sorts of odd behaviour.


Comments

Post a Comment

Popular posts from this blog

php - render data via PDO::FETCH_FUNC vs loop -

-
i've been using 2 methods render data. the first one: function name($id,$name){ return '<div id="'.$id.'">'.$name.'</div>'; } echo implode($pdo->query("select id,name user")->fetchall(pdo::fetch_func,'name')); the second one: $users = $pdo->query("select id,name user")->fetchall(pdo::fetch_obj); foreach($users $user){ echo name($user->id,$user->name); } i don't understand how pdo::fetch_func works. tried figure out. however, not well-documented. could please explain fetch mode? , also, 1 performs better? thank you. both methods wrong , have learn how use templates , how separate business logic presentation logic. $users = $pdo->query("select id,name user")->fetchall(pdo::fetch_obj); tpl::assign('users', $users); is code business logic part. then in template <?php foreach $users $row): ?> <div id="<?=$...
Read more

c# - Avoiding duplicate methods for Task and Task<T> -

-
i have logic task , task<t> . there way avoid duplicating code ? my current code following: public async task<socialnetworkuserinfo> getme() { return await wrapexception(() => new socialnetworkuserinfo()); } public async task authenticateasync() { await wrapexception(() => _facebook.authenticate()); } public async task<t> wrapexception<t>(func<task<t>> task) { try { return await task(); } catch (facebooknointernetexception ex) { throw new noresponseexception(ex.message, ex, true); } catch (facebookexception ex) { throw new socialnetworkexception("social network call failed", ex); } } public async task wrapexception(func<task> task) { try { await task(); } catch (facebooknointernetexception ex) { throw new noresponseexception(ex.message, ex, true); } catch (facebookexception ex) { throw new soci...
Read more

javascript - Which segment of a polyline was clicked? -

-
i have set sample polyline 5 segments , , i'm allowing new markers created when user clicks on polyline. i'd know if there's foolproof way determine whether new marker between markers 0 , 1, or 1 , 2 ... or between 4 , 5. i've considered checking if new marker inside bounding box, , point-in-line formulas, neither 100% precise. as google maps uses mercator projection projecting gps coordinates, can't use 'line equation' gps coordinates, because projection not linear gps points.but instead can use world coordinates linear. here have used parametric form of line equation check whether point on segment: function ispointonsegment( map, gpspoint1, gpspoint2, gpspoint ){ var p1 = map.getprojection().fromlatlngtopoint( gpspoint1 ); var p2 = map.getprojection().fromlatlngtopoint( gpspoint2 ); var p = map.getprojection().fromlatlngtopoint( gpspoint ); var t_x; var t_y; //parametric form of line equation is: //-...
Read more