C++/Vector/vector subscript indexer

Create another vector that contains a subrange of vector.

<source lang="cpp">

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

using namespace std; void show(const char *msg, vector<int> vect); int main() {

 vector<int> v(10);
 for(unsigned i=0; i < v.size(); ++i) v[i] = i*i;
 show("Contents of v: ", v);
 vector<int> v3;
 v3.assign(v.rbegin(), v.rend());
 show("v3 contains the reverse of v: ", v3);
 cout << endl;
 cout << "Size of v is " << v.size() << ". The capacity is "
      << v.capacity() << ".\n";
 v.resize(20);
 cout << "After calling resize(20), the size of v is "
      << v.size() << " and the capacity is "
      << v.capacity() << ".\n";
 v.reserve(50);
 cout << "After calling reserve(50), the size of v is "
      << v.size() << " and the capacity is "
      << v.capacity() << ".\n";
 return 0;

} void show(const char *msg, vector<int> vect) {

 cout << msg << endl;
 for(unsigned i=0; i < vect.size(); ++i)
   cout << vect[i] << endl;

}

 </source>

Loop thourgh all elements in a vector using

<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 <vector>
2. include <iostream>

using namespace std; int main() {

  vector<int> coll;
  // insert elements from -3 to 9
  for (int i=-3; i<=9; ++i) {
      coll.push_back (i);
  }
  /* print all elements
   * - NOTE: uses operator < instead of operator !=
   */
  vector<int>::iterator pos;
  for (pos=coll.begin(); pos<coll.end(); ++pos) {
      cout << *pos << " ";
  }
  cout << endl;

} /* -3 -2 -1 0 1 2 3 4 5 6 7 8 9

*/        
   
   
 </source>

Loop through all elements in a vector using operator [] instead of operator *

<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 <vector>
2. include <iostream>

using namespace std; int main() {

  vector<int> coll;
  // insert elements from -3 to 9
  for (int i=-3; i<=9; ++i) {
      coll.push_back (i);
  }
  /* print all elements
   * - NOTE: uses operator [] instead of operator *
   */
  for (int i=0; i<coll.size(); ++i) {
      cout << coll.begin()[i] << " ";
  }
  cout << endl;

} /* -3 -2 -1 0 1 2 3 4 5 6 7 8 9

*/        
   
   
 </source>

Raise all values in a vector by a given percentage

<source lang="cpp">

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

using namespace std; void raise_by_percent(vector<double>& v, double p) {

  for (int i = 0; i < v.size(); i++)
     v[i] = v[i] * (1 + p / 100);

} int main() {

  vector<double> salaries(5);
  salaries[0] = 3.0;
  salaries[1] = 6.0;
  salaries[2] = 4.0;
  salaries[3] = 7.0;
  salaries[4] = 5.0;
  raise_by_percent(salaries, 4.5);
  for (int i = 0; i < salaries.size(); i++)
     cout << salaries[i] << "\n";
  return 0;

}

 </source>

Read double from keyboard, save it to a vector and find the max value

<source lang="cpp">

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

using namespace std; int main() {

  vector<double> salaries;
  bool more = true;
  while (more)
  {  
     double s;
     cout << "Please enter a salary, 0 to quit: ";
     cin >> s;
     if (s == 0)
        more = false;
     else
        salaries.push_back(s);
  }
  double highest = salaries[0];
  int i;
  for (i = 1; i < salaries.size(); i++)
     if (salaries[i] > highest)
        highest = salaries[i];
  for (i = 0; i < salaries.size(); i++)
  {  
     if (salaries[i] == highest) 
        cout << "highest value => ";
     cout << salaries[i] << "\n";
  }
  return 0;

}

 </source>

Use indexer to add elements to a vector

<source lang="cpp">

1. include <iostream>
2. include <cassert>
3. include <algorithm>
4. include <vector>
5. include <deque>

using namespace std; int main() {

 vector<int> vector1(20);
 for (int i = 0; i < 20; ++i)
   vector1[i] = i;
 vector<int>::iterator pos;
 for (pos=vector1.begin(); pos!=vector1.end(); ++pos) {
       cout << *pos << " ";
 }
 return 0;

} /* 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

*/        
   
   
 </source>

Use indexer to reference elements in a vector

<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>

using namespace std; int main() {

   vector<int> coll;    // vector container for integer elements
   // append elements with values 1 to 6
   for (int i=1; i<=6; ++i) {
       coll.push_back(i);
   }
   // print all elements followed by a space
   for (int i=0; i<coll.size(); ++i) {
       cout << coll[i] << " ";
   }
   cout << endl;

} /* 1 2 3 4 5 6

*/        
   
   
 </source>