unordered_set end() in C++ STL (original) (raw)

Last Updated : 5 Jun, 2023

The unordered_set::end() function is a built-in function in C++ STL which returns an iterator pointing to the past-the-end-element. This iterator does not directly point to an element, rather it points to the location just after the last element.

Syntax

umap_name.end()

or,

umap_name.end(int i)

Parameters: This function takes a single integer parameter i which is optional.

Return value:

• If the parameter i is not passed then the function returns an iterator pointing to the past-the-end element. Actually, it does not point to any element of the set, but it points to the position following the last element of the container.
• If the parameter i is passed then the function returns an iterator pointing to the past-the-end element of i-th bucket. As in the previous case, it does not point to any element of the set, but it points to the position following the last element of i-th bucket. So the iterator returned by unordered_set::end() cannot be dereferenced.

Below programs illustrate the unordered_set::end() function:

Program 1:

CPP `

// CPP program to illustrate the unordered_set::end() // function

#include #include

using namespace std;

int main() { unordered_set sampleSet = { 5, 10, 15, 4, 2, 7, 8, 6 };

// Continue the loop until it points to the 
// past-the-end position returned by sampleSet.end() 
for (auto it = sampleSet.begin(); it != sampleSet.end(); 
                                                    it++) 
{ 
    cout << *it << " "; 
} 

return 0; 

}

`

Time Complexity: O(1)

Auxiliary Space: O(1)

Program 2:

CPP `

// CPP program to illustrate the // unordered_set::end() function

#include #include

using namespace std;

int main() { unordered_set sampleSet = { 5, 10, 15, 4, 2, 7, 8, 6 };

// displaying all the buckets of the set. 
// Continue the loop until it points to the 
// past-the-end position returned by sampleset.end(i) 
for (unsigned i = 0; i < sampleSet.bucket_count(); ++i) 
{ 
    cout << "Bucket " << i << " Contains: "; 
    for (auto it1 = sampleSet.begin(i); 
                    it1 != sampleSet.end(i); ++it1) 
        cout << " " << *it1; 
    cout << endl; 
} 

return 0; 

}

`

Output:

Bucket 0 Contains: Bucket 1 Contains: Bucket 2 Contains: 2 Bucket 3 Contains: Bucket 4 Contains: 4 15 Bucket 5 Contains: 5 Bucket 6 Contains: 6 Bucket 7 Contains: 7 Bucket 8 Contains: 8 Bucket 9 Contains: Bucket 10 Contains: 10

Time Complexity: O(1)

Auxiliary Space: O(1)