C++ Tutorial/set multiset/multiset find

Demonstrating multiset search member functions

<source lang="cpp">#include <iostream>

1. include <cassert>
2. include <list>
3. include <string>
4. include <set>

using namespace std; int main() {

 string s("There is no distinctly native American criminal class");
 string s2("American criminal class");
 list<char> list1(s.begin(), s.end());
 list<char> list2(s2.begin(), s2.end());
 list<char> found, not_found;
 list<char>::iterator k;
 multiset<char> multiset1;
 copy(list1.begin(), list1.end(),inserter(multiset1, multiset1.end()));
 for (k = list2.begin(); k != list2.end(); ++k)
   if (multiset1.find(*k) != multiset1.end())
     found.push_back(*k);
   else
     not_found.push_back(*k);
 for (k = found.begin(); k != found.end(); ++k)
   cout << *k;
 for (k = not_found.begin(); k != not_found.end(); ++k)
   cout << *k;
 return 0;

}</source>

American criminal class"

equal_range

<source lang="cpp">#include <iostream>

1. include <set>
2. include <algorithm>

using namespace std; int main() {

  const int SIZE = 10;
  int a[ SIZE ] = { 7, 22, 9, 1, 18, 30, 100, 22, 85, 13 };
  typedef multiset< int, less< int > > ims;
  ims intMultiset;    // ims for "integer multiset"
  pair< ims::const_iterator, ims::const_iterator > p;
  p = intMultiset.equal_range( 22 );
  cout << "\nUsing equal_range of 22"
       << "\n   Lower bound: " << *( p.first )
       << "\n   Upper bound: " << *( p.second );
  cout << endl;
  return 0;

}</source>

find returns iterator

<source lang="cpp">#include <iostream>

1. include <set>
2. include <algorithm>

using namespace std; int main() {

  const int SIZE = 10;
  int a[ SIZE ] = { 7, 22, 9, 1, 18, 30, 100, 22, 85, 13 };
  typedef multiset< int, less< int > > ims;
  ims intMultiset;    // ims for "integer multiset"
  ims::const_iterator  result = intMultiset.find( 15 );  // find returns iterator
  if ( result != intMultiset.end() ) // if iterator not at end
     cout << "Found value 15\n";     // found search value 15
  
  result = intMultiset.find( 20 );
  if ( result == intMultiset.end() )    // will be true hence
     cout << "Did not find value 20\n"; // did not find 20
  return 0;

}</source>

multiset<int>::iterator from find() method

<source lang="cpp">#include <iostream>

1. include <set>
2. include <vector>

using namespace std; template <class T> void print(T& c){

  for( typename T::iterator i = c.begin(); i != c.end(); i++ ){
     std::cout << *i << endl;
  }

} int main(){

  const int num_grades = 11;
  const int grade[num_grades] = { 2, 5, 3, 8, 9, 9, 6, 3, 5, 9, 10 };
  set<int> unique( grade, grade+num_grades );
  multiset<int> all( grade, grade+num_grades );
  print( unique );
  print( all );
  const int drop_grade = 5;
  multiset<int>::iterator spot = all.find( drop_grade );
  if( spot != all.end() ) {
     all.erase( spot );
     if( all.count( drop_grade ) == 0 )
        unique.erase( drop_grade );
  }
  else
     cout << "Couldn"t find a grade of " << drop_grade << endl;
  print( unique);
  print( all);

}</source>