How to iterate std set

Question

I have this code   std  set lt unsigned long gt   iterator it  for  it   SERVER IPS begin    it    SERVER IPS end      it        u long f   it     error here     There is no - gt first value  How I can obtain the value

User · Answer

Just use the   before it   set lt unsigned long gt   iterator it  for  it   myset begin    it    myset end      it        cout  lt  lt   it      This dereferences it and allows you to access the element the iterator is currently on

User · Answer

How do you iterate std  set   int main int argc char  argv           std  set lt int gt  mset      mset insert 1        mset insert 2       mset insert 3        for   auto it   mset begin    it    mset end    it             std  cout  lt  lt   it

User · Answer

You must dereference the iterator in order to retrieve the member of your set    std  set lt unsigned long gt   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

User · Answer

Another example for the C  11 standard   set lt int gt  data  data insert 4   data insert 5    for  const int  amp number   data    cout  lt  lt  number

User · Answer

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 lt int  gt  vec 1 2 3 4 5   int k 3  for auto itr vec begin   itr lt vec begin   k itr    cout lt  lt  itr lt  lt  quot   quot     std  unordered set lt int  gt  s 1 2 3 4 5   int k 3  int index 0  auto itr s begin    while true      if index  k  break     cout lt  lt  itr   lt  lt  quot   quot      index

[c++] How to iterate std::set?

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