C++ Tutorial/deque/deque iterator
Содержание
- 1 Create an empty deque and then assign it a sequence that is the reverse of deque
- 2 Define iterator for deque
- 3 deque<int>::iterator and deque<int>::reverse_iterator
- 4 Print the contents in reverse order using reverse_iterator and functions rbegin() and rend()
- 5 Use insert iterator adaptors to insert one deque into another by way of the copy() algorithm.
- 6 Use iterator and reverse_iterator with deque
- 7 Using the Front of a Deque
Create an empty deque and then assign it a sequence that is the reverse of deque
<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 an empty deque and then assign it a sequence that is the reverse of dq.
deque<int> dq3;
dq3.assign(dq.rbegin(), dq.rend());
show("dq3 contains the reverse of dq: ", dq3);
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>
Define iterator for deque
<source lang="cpp">// Demonstrating the generic find algorithm with a deque
- include <iostream>
- include <cassert>
- include <deque>
- include <algorithm> // For find
using namespace std;
int main() {
int x[5] = {1, 2, 3, 4, 5};
deque<int> deque1(&x[0], &x[5]);
// Search for the first occurrence of the letter e:
deque<int>::iterator i;
cout.precision(10);
for (i = deque1.begin(); i != deque1.end(); ++i)
cout << *i << endl;
return 0;
}</source>
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deque<int>::iterator and deque<int>::reverse_iterator
<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);
deque<int>::iterator itr;
deque<int>::reverse_iterator ritr;
for(itr = dq.begin(); itr != dq.end(); ++itr)
cout << *itr << " ";
for(ritr = dq.rbegin(); ritr != dq.rend(); ++ritr)
cout << *ritr << " ";
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>
Print the contents in reverse order using reverse_iterator and functions rbegin() and rend()
<source lang="cpp">#include <deque>
- include <iostream>
using namespace std; typedef deque<int> INTDEQUE; int main(void) {
INTDEQUE A;
A.push_back(1);
A.push_back(2);
A.push_back(3);
A.push_back(4);
A.push_back(5);
INTDEQUE::reverse_iterator rpi;
for(rpi = A.rbegin(); rpi != A.rend(); rpi++)
cout << *rpi << " ";
cout<< endl;
}</source>
Use insert iterator adaptors to insert one deque into another by way of the copy() algorithm.
<source lang="cpp">#include <iostream>
- include <iterator>
- include <deque>
- include <string>
using namespace std; void show(const char *msg, deque<string> dq); int main() {
deque<string> dq, dq2, dq3, dq4;
dq.push_back("A");
dq.push_back("B");
dq.push_back("C");
dq.push_back("D");
dq.push_back("E");
dq.push_back("F.");
dq2.push_back("G");
dq2.push_back("H");
dq2.push_back("I");
dq3.push_back("J");
dq3.push_back("K");
dq3.push_back("L");
dq4.push_back("M");
dq4.push_back("N");
dq4.push_back("O");
cout << dq.size() << endl;
show("Original contents of dq:", dq);
// Use an insert_iterator to insert dq2 into dq.
copy(dq2.begin(), dq2.end(), inserter(dq, dq.begin()+3));
cout << "Size of dq after inserting dq2: " << dq.size() << endl;
show("dq2:", dq);
// Use a back_insert_iterator to insert dq3 into dq.
copy(dq3.begin(), dq3.end(), back_inserter(dq));
cout << "Size of dq after inserting dq3: ";
cout << dq.size() << endl;
show("dq3:", dq);
// Use a front_insert_iterator to insert dq4 into dq.
copy(dq4.begin(), dq4.end(), front_inserter(dq));
cout << "Size of dq after inserting dq4: " << dq.size() << endl;
show("dq4:", dq);
return 0;
} void show(const char *msg, deque<string> dq) {
cout << msg << endl; for(unsigned i=0; i < dq.size(); ++i) cout << dq[i] << endl;
}</source>
Use iterator and reverse_iterator with deque
<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 <algorithm>
using namespace std; void print (int elem) {
cout << elem << " ";
} int main() {
deque<int> coll;
// insert elements from 1 to 9
for (int i=1; i<=9; ++i) {
coll.push_back(i);
}
// find position of element with value 2
deque<int>::iterator pos1;
pos1 = find (coll.begin(), coll.end(), // range
2); // value
// find position of element with value 7
deque<int>::iterator pos2;
pos2 = find (coll.begin(), coll.end(), // range
7); // value
// print all elements in range [pos1,pos2)
for_each (pos1, pos2, // range
print); // operation
cout << endl;
// convert iterators to reverse iterators
deque<int>::reverse_iterator rpos1(pos1);
deque<int>::reverse_iterator rpos2(pos2);
// print all elements in range [pos1,pos2) in reverse order
for_each (rpos2, rpos1, // range
print); // operation
cout << endl;
}</source>
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Using the Front of a Deque
<source lang="cpp">#include <deque>
- include <iostream>
- include <string>
- include <vector>
using namespace std; template <class T> void print(T& c){
for( typename T::iterator i = c.begin(); i != c.end(); i++ ){
std::cout << *i << endl;
}
} class Auction_item {
public:
Auction_item( const string& name = "nothing",
int minimum_bid = 0 );
int minimum_bid() const;
string name() const;
private:
int minimum_bid_;
string name_;
}; inline Auction_item::Auction_item( const string& name, int minimum_bid )
: name_( name ), minimum_bid_( minimum_bid )
{} inline int Auction_item::minimum_bid() const{ return minimum_bid_; } inline string Auction_item::name() const{ return name_; } int main( ) {
vector<Auction_item> v( 5 );
v[0] = Auction_item( "A", 150 );
v[1] = Auction_item( "B", 10 );
v[2] = Auction_item( "C", 75 );
v[3] = Auction_item( "D", 20 );
v[4] = Auction_item( "E", 100 );
deque<Auction_item> items;
// load auction items with cheap ones in front, expensive at back
const int min_expensive_item = 50;
for( vector<Auction_item>::iterator i = v.begin();
i != v.end(); ++i )
if( i->minimum_bid() >= min_expensive_item )
items.push_back( *i );
else
items.push_front( *i );
// sell the items
bool sell_cheap = true;
while( !items.empty() )
{
if( sell_cheap )
{
cout << items.front().name()
<< " for a minimum bid of "
<< items.front().minimum_bid() << endl;
items.pop_front();
}
else
{
cout << "Now selling: a " << items.back().name()
<< " for a minimum bid of "
<< items.back().minimum_bid() << endl;
items.pop_back();
}
// Alternate selling cheap and expensive
sell_cheap = !sell_cheap;
}
}</source>
