How to iterate std::set?

Question

I have this code:

std::set<unsigned long>::iterator it; for (it = SERVER_IPS.begin(); it != SERVER_IPS.end(); ++it) {     u_long f = it; // error here } 

There is no ->first value. How I can obtain the value?

Answer 1

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 }     

Answer 2

Another example for the C++11 standard:

set<int> data; data.insert(4); data.insert(5);  for (const int &number : data)   cout << number;