C++/Vector/vector erase

Erase first element

<source lang="cpp">

1. include <iostream>

using std::cout; using std::endl;

1. include <vector> // vector class-template definition
2. include <algorithm> // copy algorithm
3. include <iterator> // ostream_iterator iterator
4. include <stdexcept> // out_of_range exception

int main() {

  int array[ 6 ] = { 1, 2, 3, 4, 5, 6 };
  std::vector< int > integers( array, array + 6 );
  std::ostream_iterator< int > output( cout, " " );
  integers.push_back( 2 );
  integers.push_back( 3 );
  integers.push_back( 4 );
  cout << "Vector integers contains: ";
  std::copy( integers.begin(), integers.end(), output );
  // erase first element
  integers.erase( integers.begin() );
  cout << "\n\nVector integers after erasing first element: ";
  std::copy( integers.begin(), integers.end(), output );

  return 0;

} /* Vector integers contains: 1 2 3 4 5 6 2 3 4 Vector integers after erasing first element: 2 3 4 5 6 2 3 4

*/        
   
 </source>

Remove(delete) all elements in the vector

<source lang="cpp">

1. include <iostream>

using std::cout; using std::endl;

1. include <vector> // vector class-template definition
2. include <algorithm> // copy algorithm
3. include <iterator> // ostream_iterator iterator
4. include <stdexcept> // out_of_range exception

int main() {

  int array[ 6 ] = { 1, 2, 3, 4, 5, 6 };
  std::vector< int > integers( array, array + 6 );
  std::ostream_iterator< int > output( cout, " " );
  integers.push_back( 2 );
  integers.push_back( 3 );
  integers.push_back( 4 );
  cout << "Vector integers contains: ";
  std::copy( integers.begin(), integers.end(), output );
  // erase remaining elements
  integers.erase( integers.begin(), integers.end() );
  cout << "\nAfter erasing all elements, vector integers "
     << ( integers.empty() ? "is" : "is not" ) << " empty";
  return 0;

} /* Vector integers contains: 1 2 3 4 5 6 2 3 4 After erasing all elements, vector integers is empty

*/        
   
 </source>

Removes an element from an ordered vector

<source lang="cpp">

1. include <iostream>
2. include <string>
3. include <vector>

using namespace std; void erase(vector<string>& v, int pos) {

  for (int i = pos; i < v.size() - 1; i++)
     v[i] = v[i + 1];
  v.pop_back();

} void print(vector<string> v){

  for (int i = 0; i < v.size(); i++)
     cout << "[" << i << "] " << v[i] << "\n";

} int main() {

  vector<string> staff(5);
  staff[0] = "A";
  staff[1] = "B";
  staff[2] = "C";
  staff[3] = "D";
  staff[4] = "E";
  print(staff);
  int pos;
  cout << "Remove which element? ";
  cin >> pos;
  erase(staff, pos);
  print(staff);
  return 0;

}

 </source>

Removes an element from an unordered vector

<source lang="cpp">

1. include <iostream>
2. include <string>
3. include <vector>

using namespace std; void erase(vector<string>& v, int pos) {

  int last_pos = v.size() - 1;
  v[pos] = v[last_pos];
  v.pop_back();

} void print(vector<string> v){

  for (int i = 0; i < v.size(); i++)
     cout << "[" << i << "] " << v[i] << "\n";

} int main() {

  vector<string> staff(5);
  staff[0] = "A";
  staff[1] = "B";
  staff[2] = "C";
  staff[3] = "D";
  staff[4] = "E";
  print(staff);
  int pos;
  cout << "Remove which element? ";
  cin >> pos;
  erase(staff, pos);
  print(staff);
  return 0;

}

 </source>

Use unique_copy to remove duplicate words

<source lang="cpp">

/* The following code example is taken from the book

* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/

1. include <iostream>
2. include <vector>
3. include <string>
4. include <algorithm>
5. include <iterator>

using namespace std; int main() {

   vector<string> coll;
   /* read all words from the standard input
    * - source: all strings until end-of-file (or error)
    * - destination: coll (inserting)
    */
   copy (istream_iterator<string>(cin),    // start of source
         istream_iterator<string>(),       // end of source
         back_inserter(coll));             // destination
   // sort elements
   sort (coll.begin(), coll.end());
   /* print all elements without duplicates
    * - source: coll
    * - destination: standard output (with newline between elements)
    */
   unique_copy (coll.begin(), coll.end(),             // source
                ostream_iterator<string>(cout,"\n")); // destination

}

/* 

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*/       
   
 </source>