map cbegin() and cend() function in C++ STL
map::cbegin() is a built-in function in C++ STL that returns a constant iterator referring to the first element in the map container. Since map container contains the element in an ordered way, cbegin() will point to that element that will come first according to the container’s sorting criterion.
Syntax:
map_name.cbegin()
Parameters: The function does not accept any parameter.
Return Value: The function returns a constant iterator referring to the first element in the map container.
CPP
// C++ program to illustrate // the map::cbegin() function #include& lt; bits / stdc++.h & gt; using namespace std; int main() { // initialize container map& lt; int , int & gt; mp; // insert elements in random order mp.insert({ 2, 30 }); mp.insert({ 1, 40 }); mp.insert({ 3, 60 }); mp.insert({ 4, 20 }); mp.insert({ 5, 50 }); auto ite = mp.cbegin(); cout& lt; < " The first element is : " ; cout& lt; < " { " < < ite - > first& lt; < " , " < < ite - > second& lt; < " } \n& quot; ; // prints the elements cout& lt; < " \nThe map is : \n& quot; ; cout& lt; < " KEY\tELEMENT\n& quot; ; for ( auto itr = mp.cbegin(); itr != mp.cend(); ++itr) { cout& lt; < itr - > first& lt; < '\t' & lt; < itr - > second& lt; < '\n' ; } return 0; } |
The first element is: {1, 40} The map is : KEY ELEMENT 1 40 2 30 3 60 4 20 5 50
map::cend() is a built-in function in C++ STL that returns a constant iterator pointing to the theoretical element that follows the last element in the multimap. Since map container contains the element in an ordered way, cend() will point to that follows the last element according to the container’s sorting criterion.
Syntax:
map_name.cend()
Parameters: The function does not accept any parameter.
Return Value: The function returns a constant iterator pointing to the theoretical element that follows the last element in the map.
CPP
// C++ program to illustrate // the map::cend() function #include <bits/stdc++.h> using namespace std; int main() { // initialize container map< int , int > mp; // insert elements in random order mp.insert({ 2, 30 }); mp.insert({ 1, 40 }); mp.insert({ 3, 60 }); mp.insert({ 4, 20 }); mp.insert({ 5, 50 }); // print the elements cout << "\nThe map is : \n"; cout << "KEY\tELEMENT\n"; for ( auto itr = mp.cbegin(); itr != mp.cend(); ++itr) { cout << itr->first << '\t' << itr->second << '\n' ; } return 0; } |
The map is : KEY ELEMENT 1 40 2 30 3 60 4 20 5 50
Let us see the differences in a tabular form as follows:
map cbegin() | map cend() |
It is used to return a const_iterator pointing to the first element in the container. | It is used to return a const_iterator pointing to the past-the-end element in the container. |
Its syntax is as follows: const_iterator cbegin() const | Its syntax is as follows: const_iterator cend() const |
It does not take any parameters. | It does not take any parameters. |
Its complexity is constant. | Its complexity is constant. |
Its iterator validity does not change. | Its iterator validity does not change. |
Please Login to comment...