C++ Tutorial/deque/deque pop
clear dq by popping elements one at a time
<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);
// clear dq by popping elements one at a time.
cout << "Front popping elements from dq.\n";
while(dq.size() > 0) {
cout << "Popping: " << dq.front() << endl;
dq.pop_front();
}
if(dq.empty()) cout << "dq is now empty.\n";
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>
deque: constructor, size(), push_back(), pop_back(), begin(), end()
<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);
int sum = 0;
for(unsigned i=0; i < dq.size(); ++i) sum += dq[i];
double avg = sum / dq.size();
cout << avg << endl;
// Add elements to the end of dq.
dq.push_back(100);
dq.push_back(121);
show("dq after pushing elements onto the end: ", dq);
// Now use pop_back() to remove one element.
dq.pop_back();
show("dq after back-popping one element: ", dq);
cout << *dq.begin() << ", " << *(dq.end()-1) << "\n\n";
cout << *dq.rbegin() << ", " << *(dq.rend()-1) << "\n\n";
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>
Remove first and last element
<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 ("first string");
// print elements separated by newlines
copy (coll.begin(), coll.end(),ostream_iterator<string>(cout,"\n"));
cout << endl;
// remove first and last element
coll.pop_front();
coll.pop_back();
// print elements separated by newlines
copy (coll.begin(), coll.end(),ostream_iterator<string>(cout,"\n"));
cout << endl;
}</source>
first string string string string last string string string string
