Removing set from vector of sets

Question

I have a vector full of sets, I am using this piece of code to look for an int in the vector:

for(int j = 0; j <= vector.size(); ++j){
  if(vector[j].find(find) != vector[j].end())
   std::cout << "FOUND: " << propagator << "\n";
  }
}

This will output when 'find' is found, is there anyway of returning the position of that set in the vector

For example if find = 5, and my vector contained the elements:

[0] 2 3 
[1] 4 5

Is there anyway I could return the set at position 1, eventually I want to remove the whole set from the array

I have been using

for(int j = 0; j <= vector.size(); ++j){
  if(vector[j].find(find) != vector[j].end())
    vector.erase (vector.begin()+j);
  }

Answer 1

It is not difficult to return the position. For example you could use standard algorithm std::find_if and then apply function std::distance to determine the position. Or you can write the function yourself using a loop

std::vector<std::set<int>>::size_type i = 0;

while ( i < v.size() && v[i].find( key ) == v[i].end() ) ++i;

if ( i != v.size() ) v.erase( std::next( v.begin(), i ) ); 

or

auto it = std::find_if( v.begin(), v.end(),
                        [&]( const std::set<int> &s )
                        [
                           return ( s.find(key ) != s.end() );
                        } );

if ( it != v.end() ) v.erase( it );

If you need to delete all elements of the vector that contain a given value (key) then you can use standard algorithm std::remove_if along with member function erase

Answer 2

Use what you already have, no need to loop and search again:

vector.erase(vector.begin() + j);

Unless you're wanting to delete multiple sets at a time? That could get (only slightly) more complicated.

Answer 3

Additional note: you are going beyond the limit of your vector in this line:

for(int j = 0; j <= vector.size(); ++j){

You have to iterate while j < vector.size(). Although you can do it with an int, the type to do it fussily correct is size_t (that matches vector<T>::size():

for(size_t j = 0; j < vector.size(); ++j){