You must dereference the iterator in order to retrieve the member of your set.
std::set<unsigned long>::iterator it;
for (it = SERVER_IPS.begin(); it != SERVER_IPS.end(); ++it) {
u_long f = *it; // Note the "*" here
}
If you have C++11 features, you can use a range-based for loop:
for(auto f : SERVER_IPS) {
// use f here
}
One more thing that might be useful for beginners is , since std::set is not allocated with contiguous memory chunks , if someone want to iterate till kth element normal way will not work.
example:
std::vector<int > vec{1,2,3,4,5};
int k=3;
for(auto itr=vec.begin();itr<vec.begin()+k;itr++) cout<<*itr<<" ";
std::unordered_set<int > s{1,2,3,4,5};
int k=3;
int index=0;
auto itr=s.begin();
while(true){
if(index==k) break;
cout<<*itr++<<" ";
index++;
}
Just use the * before it:
set<unsigned long>::iterator it;
for (it = myset.begin(); it != myset.end(); ++it) {
cout << *it;
}
This dereferences it and allows you to access the element the iterator is currently on.
Another example for the C++11 standard:
set<int> data;
data.insert(4);
data.insert(5);
for (const int &number : data)
cout << number;
How do you iterate std::set?
int main(int argc,char *argv[])
{
std::set<int> mset;
mset.insert(1);
mset.insert(2);
mset.insert(3);
for ( auto it = mset.begin(); it != mset.end(); it++ )
std::cout << *it;
}
Source: Stackoverflow.com