C++ Tutorial/deque/deque subscript indexer

Change the values of some of deque"s elements

<source lang="cpp">#include <iostream>

1. include <deque>

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

 deque<int> dq(10);
 for(unsigned i=0; i < dq.size(); ++i) dq[i] = i*i;
 show("Contents of dq: ", dq);
 // Create another deque that contains a subrange of dq.
 deque<int> dq2(dq.begin()+2, dq.end()-4);
 // Display the contents of dq2 by using an iterator.
 show("dq2 contains a subrange of dq: ", dq2);
 cout << endl;
 // Change the values of some of dq2"s elements.
 dq2[1] = 100;
 dq2[2] = 88;
 dq2[4] = 99;
 show("After the assignments, dq2 now contains: ", dq2);
 cout << endl;
 return 0;

} // Display the contents of a deque<int>. void show(const char *msg, deque<int> q) {

 cout << msg;
 for(unsigned i=0; i < q.size(); ++i)
   cout << q[i] << " ";
 cout << "\n";

}</source>

Insert "value" into every element but the first

<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 <deque>
3. include <string>
4. include <algorithm>
5. include <iterator>

using namespace std; int main() {

   // create empty deque of strings
   deque<string> coll;
   // insert several elements
   coll.assign (3, string("string"));
   coll.push_back ("last string");
   coll.push_front ("BBB string");
   coll.push_front ("CCC string");
   coll.push_front ("AAA string");
   // print elements separated by newlines
   copy (coll.begin(), coll.end(),ostream_iterator<string>(cout,"\n"));
   cout << endl;
   // insert ""another"" into every element but the first
   for (unsigned i=1; i<coll.size(); ++i) {
       coll[i] = "another " + coll[i];
   }
   // print elements separated by newlines
   copy (coll.begin(), coll.end(),ostream_iterator<string>(cout,"\n"));
   cout << endl;

}</source>

AAA string
CCC string
BBB string
string
string
string
last string
AAA string
another CCC string
another BBB string
another string
another string
another string
another last string

Print out a deque, reference its content by index,

<source lang="cpp">#include <deque>

1. include <iostream>

using namespace std; typedef deque<char> CHARDEQUE; void print_contents(CHARDEQUE deque, char*); int main(void){

  CHARDEQUE  a;  
  if(a.empty())  
    cout << "a is empty" << endl;
  else
    cout << "a is not empty" << endl;
  a.push_back("A");
  a.push_back("B");
  a.push_back("C");
  a.push_back("D");
  if(a.empty())  
      cout << "a is empty" << endl;
  else
      cout << "a is not empty" << endl;
  print_contents(a,"a");      
  cout << "The first element of a is  " << a[0] << endl;
  cout << "The first element of a is  " << a.at(0) << endl;
  cout << "The last element of a is  " << a[a.size()-1] << endl;
  cout << "The last element of a is  " << a.at(a.size()-1) << endl;

} void print_contents(CHARDEQUE deque, char *name){

  CHARDEQUE::iterator pdeque;
  cout << "The contents of "<< name << " : ";
  for(pdeque = deque.begin(); pdeque != deque.end(); pdeque++)
    cout << *pdeque <<" ";
  cout << endl;

}</source>

Use indexer to add elements to a deque

<source lang="cpp">#include <iostream>

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

using namespace std; int main() {

 deque<int>  deque1(5);
 for (int i = 0; i < 5; ++i)
   deque1[i] = i + 5;
 deque<int>::iterator pos;
 for (pos=deque1.begin(); pos!=deque1.end(); ++pos) {
       cout << *pos << " ";
 }
 return 0;

}</source>

5 6 7 8 9 "

Use subscript operator to modify element at location 1

<source lang="cpp">#include <iostream> using std::cout; using std::endl;

1. include <deque> // deque class-template definition
2. include <algorithm> // copy algorithm
3. include <iterator> // ostream_iterator

int main() {

  std::deque< double > values; // create deque of doubles
  std::ostream_iterator< double > output( cout, " " );
  // insert elements in values
  values.push_front( 2.2 );
  values.push_front( 3.5 );
  values.push_back( 1.1 );
  cout << "values contains: ";
  std::copy( values.begin(), values.end(), output );
  // use subscript operator to modify element at location 1
  values[ 1 ] = 5.4;
  cout << "\nAfter values[ 1 ] = 5.4, values contains: ";
  std::copy( values.begin(), values.end(), output );
  cout << endl;
  return 0;

}</source>

values contains: 3.5 2.2 1.1
After values[ 1 ] = 5.4, values contains: 3.5 5.4 1.1

Use subscript operator to obtain elements of values

<source lang="cpp">#include <iostream> using std::cout; using std::endl;

1. include <deque> // deque class-template definition
2. include <algorithm> // copy algorithm
3. include <iterator> // ostream_iterator

int main() {

  std::deque< double > values; // create deque of doubles
  std::ostream_iterator< double > output( cout, " " );
  values.push_front( 2.2 );
  values.push_front( 3.5 );
  values.push_back( 1.1 );
  cout << "values contains: ";
  // use subscript operator to obtain elements of values
  for ( int i = 0; i < values.size(); i++ )
     cout << values[ i ] << " ";
  cout << endl;
  return 0;

}</source>

values contains: 3.5 2.2 1.1