cppreference.com > C++ Vectors > assign assign Syntax:
      #include <vector>
      void assign( size_type num, const TYPE& val );
      void assign( input_iterator start, input_iterator end );
The assign() function either gives the current vector the values from start to end, or gives it num copies of val. This function will destroy the previous contents of the vector. For example, the following code uses assign() to put 10 copies of the integer 42 into a vector:
     vector<int> v;
     v.assign( 10, 42 );
     for( int i = 0; i < v.size(); i++ ) {
       cout << v[i] << " ";
     }
     cout << endl;
The above code displays the following output:
     42 42 42 42 42 42 42 42 42 42
The next example shows how assign() can be used to copy one vector to another:
     vector<int> v1;
     for( int i = 0; i < 10; i++ ) {
       v1.push_back( i );
     }

     vector<int> v2;
     v2.assign( v1.begin(), v1.end() );

     for( int i = 0; i < v2.size(); i++ ) {
       cout << v2[i] << " ";
     }
     cout << endl;
When run, the above code displays the following output:
     0 1 2 3 4 5 6 7 8 9
Related topics: (C++ Strings) assign insert push_back (C++ Lists) push_front