c++ - When is constructor's code of a class defined in global space running? - 


class testclass { public:     int x, y;     testclass();  };  testclass::testclass() {     cout << "testclass ctor" << endl; }  testclass globaltestclass;  int main() {         cout << "main " << endl;       return 0; }

in code known first output "testclass ctor".

my question: ctor function call codes run before main() (i mean, entry point change ?) , or right after main() , before executable statements or there different mechanism ? (sorry english)

the question stated not meaningful, because

  • main not machine code level entry point program (main called same code e.g. executes constructors of non-local static class type variables), and
  • the notion of “right after main() , before executable statements” isn't meaningful: executable statements in main.

generally, in practice can count on static variable being initialized before main in concrete example, standard not guarantee that.

c++11 §3.6.2/4:

” implementation-defined whether dynamic initialization of non-local variable static storage duration done before first statement of main. if initialization deferred point in time after first statement of main, shall occur before first odr-use (3.2) of function or variable defined in same translation unit variable initialized.

it's fine point whether automatic call of main qualifies odr-use. think not, because 1 special property of main cannot called (in valid code), , address cannot taken.

apparently above wording in support of dynamically loaded libraries, , constitutes support of such libraries.

in particular, wary of using thread local storage dynamically loaded libraries, @ least until learned more guarantees offered standard in respect.


Comments

Post a Comment

Popular posts from this blog

c# - Validate object ID from GET to POST -

i have method allows user access comment have made on site. have post method lets them update comment. my normal solution send entire comment model through, let them update it, update on database when post back. involve sending commentid through in hiddenfor , can manipulated. how can verify commentid sent in get method same i'm getting in post , not able alter comment wish? how can verify commentid sent in method same i'm getting in post? basically have validate following things in post - user logged-in user. authenticated users post comments. commentid in post , should valid commentid , should present in database. userid associated logged-in user should same userid associated comment . comment should contain userid column, can check @ time of update. to make sure update happens comment has been sent in get - hold commentid in session , in post action compare commentid value in session .
Read more

node.js - Custom Model Validator SailsJS -

when using custom model validator checks record within model. return within spread doesn't seem end control flow. //post.js model /** * custom validator **/ types: { isuservalid: function(user_id) { var promise = require('bluebird'); promise.all([ user.findone({id: user_id}) ]) .spread(function(user) { console.log(user); if (user === null || user === undefined) { console.log('failed'); return false; }else{ console.log('passed'); return true; } }); } }, my response standard validation failed response. { "error": "e_validation", "status": 400, "summary": "1 attribute invalid", "model": "post", "invalidattributes": { "owner": [ { "rule": "isuservalid", ...
Read more

php - Find a regex to take part of Email -

i have following emails need extract part from: bestellnummer xxx: 1 von xxx, 1er pack ------------- anfang der nachricht ------------- foo bar baz foo bar baz // <<<<< need text here ------------- ende der nachricht ------------- ------------- anfang der nachricht ------------- foo bar baz foo bar baz ------------- ende der nachricht ------------- there 0 unlimited occurences of ------------- anfang der nachricht ------------- ------------- ende der nachricht ------------- and i'm able extract first part regex: $re = "/------------- .*? -------------.?(.*?).?------------- .*? -------------/s"; but, i'm quite new on learning regex, i'm pretty sure there must better regex extract part (foo bar baz foo bar baz) of text between ------------- anfang der nachricht ------------- ------------- ende der nachricht ------------- as can in different languages, i'm using .? to match between hyphens. i...
Read more