c++11 - How can I push back onto a vector an instance of a class in C++ -

-

bear me please, first time posting. have 3 classes. class suppliers has set of class parent. class parent has vector of class location , class location has data memebers. ex (this pseudo code, not actual code. i've shown simplicity sake):

class suppliers{ set<parent> setter; }; class parent{ vector<location> loc; };

`

the following constructor of location class created. run no problems until lines hit 2 lines iterators. trying find specific parent , push new location onto parent 'loc' vector. pass in iterator i've found reference. try push new instance of location class following error.

data.cpp:139:33: error: passing 'const std::vector' 'this' argument of 'void std::vector<_tp, _alloc>::push_back(const value_type&) [with _tp = location; _alloc = std::allocator; std::vector<_tp, _alloc>::value_type = location]' discards qualifiers [-fpermissive]

the last line gives error says cannot alter read-only object. i'm confused why read object. did research , thought needed add copy constructor. however, caused more problems solved. ideas?

location::location(set<parent>::iterator &it, vector<string> v){     sup_id = v[0];  address1 = v[2];  address2 = v[3];  city = v[4];  state = v[5];  country = v[6];  zip = v[7];  ((*it).loc).push_back(*this);  ((*it).num)++;    }

the problem set sorted. if you'd allowed change element through iterator, mean potentially invalidate iterator , therefore since c++11, iterator of set constant bidirectional iterator , thereby has same semantics set's const_iterator.

the solution, although ugly, remove, modify , re-insert element. there proposal allow modification of keys of associative containers, don't know if there progress in getting standardized.


Comments

Post a Comment

Popular posts from this blog

python - TypeError: start must be a integer -

-
i trying draw 5 turtles, getting typeerror on line 25. here code: import turtle wn = turtle.screen() redrose = turtle.turtle() color = input("what background color be?") fillcolor_f = input("what color of rose be?") redrose.hideturtle() redrose.speed(30) redrose.penup() redrose.left(180) redrose.forward(175) redrose.right(90) redrose.forward(30) redrose.right(90) redrose.pendown() def drawrose(red): redrose.color("pink") redrose.fillcolor(fillcolor_f) redrose.fill(true) in range(red): redrose.forward(i) redrose.right(49) in range(5): drawrose(redrose) redrose.penup() redrose.forward(350) redrose.right(144) redrose.pendown() redrose.fill(false) drawrose(50) wn.bgcolor(color) i trying draw 5 roses, produces errors. doing in interactivepython.org. you recursively calling drawrose wrong parameter. on line 23 ( for in range(red): ) expect red integer...
Read more

c# - DevExpress RepositoryItemComboBox BackColor property ignored -

-
i have following code almost works properly; private void cbstatus_drawitem(object sender, listboxdrawitemeventargs e) { string item = e.item string; if (item != null) { switch (item) { case "1": e.appearance.forecolor = color.green; e.appearance.backcolor = color.green; break; case "2": e.appearance.forecolor = color.orange; e.appearance.backcolor = color.orange; break; case "3": e.appearance.forecolor = color.red; e.appearance.backcolor = color.red; break; } } } when dropdown shown, items forecolor correct, backcolor remains whatever backcolor of theme is; i.e. if i've got set dark theme, backcolor dark, cells in gridview, rather being green/orange/red. i've tried setting e.appearance.options.usebackcolor trying set e....
Read more

django - Creating multiple model instances in DRF3 -

-
1) create multiple model instances 1 api call, asked here: how create multiple model instances django rest framework? tried solution named in link, no success. i trying upload multiple files in 1 api call. result: files uploaded (only once overwrote perform_create) 1 instance created (if send 2 files, latter created instance). my code: class fileuploadserializer(serializers.modelserializer): def __init__(self, *args, **kwargs): many = kwargs.pop('many', true) super(fileuploadserializer, self).__init__(many=many, *args, **kwargs) class meta: model = fileupload read_only_fields = ('created', 'datafile', 'owner') class fileuploadviewset(viewsets.modelviewset): queryset = fileupload.objects.all() serializer_class = fileuploadserializer parser_classes = (multipartparser, formparser, ) def perform_create(self, serializer): file_list = self.request.data.getlist('file') ...
Read more