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==Change the values of some of deque"s elements==

<source lang="cpp">#include <iostream>
#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.
*/
#include <iostream>
#include <deque>
#include <string>
#include <algorithm>
#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>
<pre class=codeResult>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</pre>

==Print out a deque, reference its content by index,==

<source lang="cpp">#include <deque>
#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>
#include <cassert>
#include <algorithm>
#include <vector>
#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>
<pre class=codeResult>5 6 7 8 9 "</pre>

==Use subscript operator to modify element at location 1==

<source lang="cpp">#include <iostream>
using std::cout;
using std::endl;
#include <deque> // deque class-template definition
#include <algorithm> // copy algorithm
#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>
<pre class=codeResult>values contains: 3.5 2.2 1.1
After values[ 1 ] = 5.4, values contains: 3.5 5.4 1.1</pre>

==Use subscript operator to obtain elements of values==

<source lang="cpp">#include <iostream>
using std::cout;
using std::endl;
#include <deque> // deque class-template definition
#include <algorithm> // copy algorithm
#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>
<pre class=codeResult>values contains: 3.5 2.2 1.1</pre>

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