C++/Vector/vector iterator

Change contents of vector through an iterator

<source lang="cpp">

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

using namespace std; int main() {

 vector<char> v(10); // create a vector of length 10
 vector<char>::iterator p; // create an iterator
 int i;
 // assign elements in vector a value
 p = v.begin();
 i = 0;
 while(p != v.end()) {
   *p = i + "a";
   p++;
   i++;
 }
 // display contents of vector
 cout << "Original contents:\n";
 p = v.begin();
 while(p != v.end()) {
   cout << *p << " ";
   p++;
 }
 cout << "\n\n";

 // change contents of vector
 p = v.begin();
 while(p != v.end()) {
   *p = toupper(*p);
   p++;
 }

 // display contents of vector
 cout << "Original contents:\n";
 p = v.begin();
 while(p != v.end()) {
   cout << *p << " ";
   p++;
 }
 cout << "\n\n";
 return 0;

} /* Original contents: a b c d e f g h i j Original contents: A B C D E F G H I J

*/
       
   
   
 </source>

const_iterator from different containers

<source lang="cpp">

1. include <algorithm>
2. include <vector>
3. include <list>
4. include <iostream>

using namespace std; int main () {

   vector <int> v;
   for (int nNum = -9; nNum < 10; ++ nNum)
       v.push_back (nNum);
   v.push_back (9);
   v.push_back (9);
   list <int> l;
   for (int nNum = -4; nNum < 5; ++ nNum)
       l.push_back (nNum);
   vector <int>::const_iterator vi;
   for ( vi = v.begin (); vi != v.end (); ++ vi )
       cout << *vi << " ";
   list <int>::const_iterator li;
   for ( li = l.begin (); li != l.end (); ++ li )
       cout << *li << " ";
   return 0;

}

 </source>

Display contents of vector through an iterator

<source lang="cpp">

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

using namespace std; int main() {

 vector<char> v(10); // create a vector of length 10
 vector<char>::iterator p; // create an iterator
 int i;
 // assign elements in vector a value
 p = v.begin();
 i = 0;
 while(p != v.end()) {
   *p = i + "a";
   p++;
   i++;
 }
 // display contents of vector
 cout << "Original contents:\n";
 p = v.begin();
 while(p != v.end()) {
   cout << *p << " ";
   p++;
 }
 cout << "\n\n";
 return 0;

} /* Original contents: a b c d e f g h i j

*/        
   
   
 </source>

interator operator for vector

<source lang="cpp">

1. include <vector>

using namespace std; int main(int argc, char** argv) {

 vector<int> intVector(10, 0);
 vector<int>::iterator it = intVector.begin();
 it += 5;
 --it;
 *it = 4;
 return (0);

}

 </source>

Loop through all elements in a vector in reverse order by using rbegn, rend

<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 <algorithm>
4. include <iterator>

using namespace std; int main() {

   vector<int> coll;
   // insert elements from 1 to 9
   for (int i=1; i<=9; ++i) {
       coll.push_back(i);
   }
   // print all element in reverse order
   copy (coll.rbegin(), coll.rend(),        // source
         ostream_iterator<int>(cout," "));  // destination
   cout << endl;

} /* 9 8 7 6 5 4 3 2 1

*/        
   
   
 </source>

Use const_iterator to loop through the vector

<source lang="cpp">

1. include <iostream>

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

1. include <vector>

using std::vector; int main() {

  int array[ 6 ] = { 1, 2, 3, 4, 5, 6 }; // initialize array
  vector< int > integers; // create vector of ints
  integers.push_back( 2 );
  integers.push_back( 3 );
  integers.push_back( 4 );
  vector< int >::const_iterator constIterator;
  // display vector elements using const_iterator
  for ( constIterator = integers.begin();
     constIterator != integers.end(); ++constIterator )
     cout << *constIterator << " ";
  cout << endl;
  return 0;

} /* 2 3 4

*/        
   
   
 </source>

vector.begin, vector.end returns the iterators

<source lang="cpp">

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

using namespace std;

int main(void) {

   const int VECTOR_SIZE = 8 ;
   typedef vector<int> IntVector ;
   typedef IntVector::iterator IntVectorIt ;
   IntVector Numbers(VECTOR_SIZE) ;
   IntVectorIt start, end, it ;
   Numbers[0] = 4;
   Numbers[1] = 1;
   Numbers[2] = 7;
   Numbers[3] = 3;
   Numbers[4] = 1;
   Numbers[5] = 6;
   Numbers[6] = 9;
   Numbers[7] = 10;
   start = Numbers.begin() ;   
   end = Numbers.end() ;       
   for(it = start; it != end; it++)
       cout << *it << " " ;
   random_shuffle(start, end) ;
   for(it = start; it != end; it++)
       cout << *it << " " ;

}

 </source>