cppreference.com > C++ Lists > Container constructors Container constructors Syntax:
      #include <list>
      container();
      container( const container& c );
      container( size_type num, const TYPE& val = TYPE() );
      container( input_iterator start, input_iterator end );
      ~container();
The default list constructor takes no arguments, creates a new instance of that list. The second constructor is a default copy constructor that can be used to create a new list that is a copy of the given list c. The third constructor creates a list with space for num objects. If val is specified, each of those objects will be given that value. For example, the following code creates a vector consisting of five copies of the integer 42:
     vector<int> v1( 5, 42 );
The last constructor creates a list that is initialized to contain the elements between start and end. For example:
     // create a vector of random integers
     cout << "original vector: ";
     vector<int> v;
     for( int i = 0; i < 10; i++ ) {
       int num = (int) rand() % 10;
       cout << num << " ";
       v.push_back( num );
     }
     cout << endl;

     // find the first element of v that is even
     vector<int>::iterator iter1 = v.begin();
     while( iter1 != v.end() && *iter1 % 2 != 0 ) {
       iter1++;
     }

     // find the last element of v that is even
     vector<int>::iterator iter2 = v.end();
     do {
       iter2--;
     } while( iter2 != v.begin() && *iter2 % 2 != 0 );

     cout << "first even number: " << *iter1 << ", last even number: " << *iter2 << endl;

     cout << "new vector: ";
     vector<int> v2( iter1, iter2 );
     for( int i = 0; i < v2.size(); i++ ) {
       cout << v2[i] << " ";
     }
     cout << endl;
When run, this code displays the following output:
     original vector: 1 9 7 9 2 7 2 1 9 8
     first even number: 2, last even number: 8
     new vector: 2 7 2 1 9
All of these constructors run in linear time except the first, which runs in constant time. The default destructor is called when the list should be destroyed.