C++ Tutorial/vector/vector reverse iterator

Declare a reverse iterator to the vector of char

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

1. include <vector>

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

 vector<char> v;
 // Declare an iterator to a vector<char>.
 vector<char>::iterator itr;
 // Obtain an iterator to the start of v.
 itr = v.begin();
 // Insert characters into v. An iterator to the inserted object is returned.
 itr = v.insert(itr, "A");
 itr = v.insert(itr, "B");
 v.insert(itr, "C");
 // Display the contents of v.
 show("The contents of v: ", v);
 // Declare a reverse iterator.
 vector<char>::reverse_iterator ritr;
 // Use a reverse iterator to show the contents of v in reverse.
 cout << "Here is v in reverse: ";
 for(ritr = v.rbegin(); ritr != v.rend(); ++ritr)
   cout << *ritr << " ";
 cout << "\n\n";
 return 0;

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

 vector<char>::iterator itr;
 cout << msg << endl;
 for(itr=vect.begin(); itr != vect.end(); ++itr)
   cout << *itr << endl;

}</source>

Illustrating normal and reverse iteration.

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

1. include <vector>
2. include <list>

using namespace std; int main() {

 cout << "Normal and reverse iteration through a vector:\n";
 vector<int> vector1;
 vector1.push_back(2);
 vector1.push_back(3);
 vector1.push_back(5);
 vector1.push_back(7);
 vector1.push_back(11);
 cout << "Elements in normal (forward) order:  ";
 vector<int>::iterator i;
 for (i = vector1.begin(); i != vector1.end(); ++i)
    cout << *i << "  ";
 cout << endl;
 cout << "Elements in reverse order:           ";
 vector<int>::reverse_iterator r;
 for (r = vector1.rbegin(); r != vector1.rend(); ++r)
    cout << *r << "  ";
 cout << endl;

 cout << "Normal and reverse iteration through a list:\n";
 list<int> list1(vector1.begin(), vector1.end());
 cout << "Elements in normal (forward) order:  ";
 for (i = vector1.begin(); i != vector1.end(); ++i)
    cout << *i << "  ";
 cout << endl;
 cout << "Elements in reverse order:           ";
 for (r = vector1.rbegin(); r != vector1.rend(); ++r)
    cout << *r << "  ";
 cout << endl;
 return 0;

}</source>

Normal and reverse iteration through a vector:
Elements in normal (forward) order:  2  3  5  7  11
Elements in reverse order:           11  7  5  3  2
Normal and reverse iteration through a list:
Elements in normal (forward) order:  2  3  5  7  11
Elements in reverse order:           11  7  5  3  2

Traverse reverse backward

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

1. include <iostream>

using namespace std; vector<double> makevector(int size){

 vector<double> result;
 for (int i=1; i<=size; i++) { 
   result.push_back(double(i)); 
 } 
 return result; 

} void print(const vector<double>& l) {

 cout << "Size of vector is: " << l.size() << endl; 
 vector<double>::const_iterator i; 
 for (i=l.begin(); i!=l.end(); i++) 
 { 
   cout << (*i) << " "; 
 } 
 cout << endl; 

} int main() {

 vector<double> vector1=makevector(5); 
 vector<double>::iterator bi; 
 bi=vector1.begin();           // Set iterator 
 while (bi!=vector1.end()) cout << (*bi++) << " "; 
 // Traverse backward 
 bi=(vector1.end()); 
 do { 
   cout << (*--bi) << " "; 
 } 
 while (bi!=vector1.begin()); 
 cout << endl << endl; 
 bi=vector1.begin(); 
 cout << *bi << " ";                // First element 
 cout << *(bi+=3) << " ";           // 1+3 is 4th element 
 cout << *(bi-=1) << " ";           // 4-1 is third element 
 cout << bi[-1] << " ";             // 3-1 is second element 
 cout << bi[1] << endl << endl;     // 3+1 is fourth element 

}</source>

Traverse reverse randomly

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

1. include <iostream>

using namespace std; vector<double> makevector(int size){

 vector<double> result;
 for (int i=1; i<=size; i++) { 
   result.push_back(double(i)); 
 } 
 return result; 

} void print(const vector<double>& l) {

 cout << "Size of vector is: " << l.size() << endl; 
 vector<double>::const_iterator i; 
 for (i=l.begin(); i!=l.end(); i++) 
 { 
   cout << (*i) << " "; 
 } 
 cout << endl; 

} int main() {

 vector<double> vector1=makevector(5); 
 vector<double>::iterator bi; 
 vector<double>::reverse_iterator ri; 
 ri=vector1.rbegin();          // Set iterator 
 while (ri!=vector1.rend()) cout << (*ri++) << " "; 
 cout << endl << endl; 
 // Traverse reverse backward 
 cout << "Traverse reverse backward" << endl; 
 ri=(vector1.rend()); 
 do 
 { 
   cout << (*--ri) << " "; 
 } 
 while (ri!=vector1.rbegin()); 
 cout << endl << endl; 

}</source>

Use a reverse iterator to show the contents of v in reverse

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

1. include <vector>

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

 vector<char> v;
 // Declare an iterator to a vector<char>.
 vector<char>::iterator itr;
 // Obtain an iterator to the start of v.
 itr = v.begin();
 // Insert characters into v. An iterator to the inserted object is returned.
 itr = v.insert(itr, "A");
 itr = v.insert(itr, "B");
 v.insert(itr, "C");
 // Display the contents of v.
 show("The contents of v: ", v);
 // Declare a reverse iterator.
 vector<char>::reverse_iterator ritr;
 // Use a reverse iterator to show the contents of v in reverse.
 cout << "Here is v in reverse: ";
 for(ritr = v.rbegin(); ritr != v.rend(); ++ritr)
   cout << *ritr << " ";
 cout << "\n\n";
 return 0;

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

 vector<char>::iterator itr;
 cout << msg << endl;
 for(itr=vect.begin(); itr != vect.end(); ++itr)
   cout << *itr << endl;

}</source>