The cend function in C++ map is utilized to provide a constant iterator pointing to the element following the last element in the map.
Note:-This is a placeholder. No element exists in this location and attempting to access is undefined behavior.
Syntax
const_iterator cend() const noexcept; //since C++ 11
Note: A const_iterator is an iterator thacpp tutorials to constant content.
Parameter
Return value
It provides a constant iterator pointing to the element following the final one in the map.
Example 1
Let's see a simple example for cend function.
#include <iostream>
#include <map>
using namespace std;
int main ()
{
map<char,int> mymap;
mymap['b'] = 100;
mymap['a'] = 200;
mymap['c'] = 300;
// print content:
cout << "mymap contains:";
for (auto it = mymap.cbegin(); it != mymap.cend(); ++it)
cout << " [" << (*it).first << ':' << (*it).second << ']';
cout << '\n';
return 0;
}
Output:
mymap contains: [a:200] [b:100] [c:300]
In the example provided, the cend method is employed to retrieve an iterator pointing to the element following the last one in the map named mymap.
Example 2
Let's examine a basic illustration of iterating through a map using a for-each loop.
#include <iostream>
#include <map>
#include <string>
#include <iterator>
#include <algorithm>
using namespace std;
int main() {
map<string, int> m;
m["Room1"] = 100;
m["Room2"] = 200;
m["Room3"] = 300;
// Create a map iterator and point to beginning of map
map<string, int>::iterator it = m.begin();
// Iterate over a map using std::for_each and Lambda function
for_each(m.cbegin(), m.cend(),
[](pair<string, int> element){
// Accessing KEY from element
string word = element.first;
// Accessing VALUE from element.
int count = element.second;
cout<<word<<" = "<<count<<endl;
});
return 0;
}
Output:
Room1 = 100
Room2 = 200
Room3 = 300
In the previous example, we employed an STL algorithm called std::for-each to sequentially go through the map. This process involves iterating over each element within the map and executing the designated callback function.
Example 3
Let's examine a basic illustration of iterating through a map utilizing a while loop.
#include <iostream>
#include <map>
#include <string>
int main()
{
using namespace std;
map<int,string> mymap = {
{ 100, "Nikita"},
{ 200, "Deep" },
{ 300, "Priya" },
{ 400, "Suman" },
{ 500, "Aman" }};
map<int, string>::const_iterator it; // declare an iterator
it = mymap.cbegin(); // assign it to the start of the vector
while (it != mymap.cend()) // while it hasn't reach the end
{
cout << it->first << " = " << it->second << "\n";
// print the value of the element icpp tutorials to
++it; // and iterate to the next element
}
cout << endl;
}
Output:
100 = Nikita
200 = Deep
300 = Priya
400 = Suman
500 = Aman
In the provided instance, the cend method is employed to retrieve a constant iterator that points to the element following the final entry in the mymap map.
Example 4
Let's see a simple example.
#include <iostream>
#include <string>
#include <map>
using namespace std;
int main ()
{
map<int,int> mymap = {
{ 10, 10},
{ 20, 20 },
{ 30, 30 } };
cout<<"Elements are:" <<endl;
for (auto it = mymap.cbegin(); it != mymap.cend(); ++it)
cout << it->first
<< " + "
<< it->second
<< " = "
<<it->first + it->second
<< '\n';
auto ite = mymap.cend();
cout << "end element (point next to the last): ";
cout << "{" << ite->first << ", "
<< ite->second << "}\n";
return 0;
}
Output:
Elements are:
10 + 10 = 20
20 + 20 = 40
30 + 30 = 60
end element (point next to the last): {3, 0}
In the example provided, the cend method is employed to retrieve a constant iterator that points to the element following the final entry in the map named mymap.
