CODEWITHSUNDEEP
c++vectorerase
Katie
Katie

Reputation: 31

vector::erase doesn't work in class method, but works in main; No Compiler Error, just unexpected results

I have the following statement in a file x.cpp. Suppliers and location are classes I created. If I write in my main.cpp

Suppliers s;
s.clean_up();

and in file x.cpp

void Suppliers::clean_up(){
    for(auto i : setter){
        i.second.clear();}}

Setter is a public data member of Suppliers

 map<std::string,std::vector<location>> setter

The map is not cleared when I try to print it. On the contrary if I have the following in my main, the values in my map are cleared as I would expect.

Suppliers s;
for (auto item : s.setter){
     item.second.clear();}

I have no Compiler errors, in one case the location vector is erased and in one case it isn't. The only thing I can think of is that the instance of setter aren't the same. But because I'm using a method I can't see why this wouldn't work. Any help would be great, thanks in advance!

Upvotes: 1

Views: 74

Answers (1)

Cory Kramer
Cory Kramer

Reputation: 117886

You should iterate using references to your map items

for(auto& i : setter)
{
    i.second.clear();
}

Otherwise i will be a copy of each std::pair<std::string, std::vector<location>>. So it will clear() the vector of the copy, not the actual instance in the map.

Upvotes: 6

Related Questions