The unordered_multimap::cbegin() is a built-in function in C++ STL which returns a constant iterator pointing to the first element in the container or to the first element in one of its bucket.
Syntax:
unordered_multimap_name.cbegin(n)
Parameters: The function accepts one parameter. If a parameter is passed, it returns a constant iterator pointing to the first element in the bucket. If no parameter is passed, then it returns a constant iterator pointing to the first element in the unordered_multimap container.
Return Value: It returns a constant iterator. It cannot be used to change the value of the unordered_multimap element.
Below programs illustrates the above function:
Program 1:
// C++ program to illustrate the // unordered_multimap::cbegin() #include <bits/stdc++.h> using namespace std;
int main()
{ // declaration
unordered_multimap< int , int > sample;
// inserts key and element
sample.insert({ 1, 2 });
sample.insert({ 3, 4 });
sample.insert({ 3, 4 });
sample.insert({ 2, 3 });
sample.insert({ 2, 3 });
// prints all key and element
cout << "Key and Elements : \n" ;
for ( auto it = sample.begin(); it != sample.end(); it++)
cout << " " << it->first << "\t " << it->second << endl;
auto it = sample.begin();
// print the first element
cout << "\nThe first element and key: " << it->first << " " ;
cout << it->second;
return 0;
} |
Key and Elements : 2 3 2 3 1 2 3 4 3 4 The first element and key: 2 3
Program 2:
// C++ program to illustrate the // unordered_multimap::cbegin(bucket) #include <bits/stdc++.h> using namespace std;
int main()
{ // declaration
unordered_multimap< int , int > sample;
// inserts element
sample.insert({ 1, 2 });
sample.insert({ 3, 4 });
sample.insert({ 3, 4 });
sample.insert({ 2, 3 });
sample.insert({ 2, 3 });
// prints all element
cout << "Key and Elements of first bucket: \n" ;
for ( auto it = sample.cbegin(1); it != sample.cend(1); it++)
cout << " " << it->first << "\t " << it->second << endl;
auto it = sample.cbegin(1);
// print the first element
cout << "\nThe first element and key in first bucket: "
<< it->first << " " ;
cout << it->second;
return 0;
} |
Key and Elements of first bucket: 1 2 The first element and key in first bucket: 1 2