In the C++ programming language, the multiset end function is a function that is present in the Standard Template Library (STL). It is used to return an iterator that is next to the last entry in the multiset container. It helps to make the boundary of the container. We can use this function to iterate, compare, and understand the range of the multiset container.
Note:- This is a placeholder. No element exists in this location, and attempting to access it is undefined behavior.
Syntax:
It has the following syntax:
iterator end(); //until C++ 11
iterator end() const; //until C++ 11
iterator end() noexcept; //since C++ 11
iterator end() const noexcept; //since C++ 11
In this syntax,
- Parameter: It does not hold any parameter.
- Return value: It returns an iterator thacpp tutorials to the last element of the multiset.
Complexity Analysis
If we want to perform any operation using the multiset end function, it takes only constant time complexity, i.e., O(1).
Simple C++ Multiset end function Example
Let's take an example to demonstrate the multiset end function, where we have worked on string values in C++ .
Example
#include <iostream>
#include <set>
using namespace std; //using standard namespace
int main () //main function
{
multiset<string> mymultiset = {"Java", "C++", "Java", "C++"};
// display content:
for (multiset<string>::iterator it=mymultiset.begin(); it!=mymultiset.end(); ++it)
cout << *it<< '\n';
return 0;
}
Output:
C++
C++
Java
Java
Explanation:
In the above example, we create a multiset of strings and initialize it with several values. When we use a for loop, we can iterate from the begin function to the end function. The begin function represents the first element of the string, and the end function represents the position just after the last element. During the iteration in the multiset, each element is printed until the iterator reaches the end function. Therefore, the output prints all the available elements in sorted order, which demonstrates that the end function is used only as the stopping boundary.
C++ Multiset end Function Example using for-each loop
Let's consider a simple example to iterate over the multiset using a for-each loop in C++.
Example
#include <iostream>
#include <set>
using namespace std; //using standard namespace
int main() //main function
{
multiset<int> c;
c.insert(5);
c.insert(2);
c.insert(1);
c.insert(1);
c.insert(0);
c.insert(0);
c.insert(2);
multiset<int>::iterator i = c.begin();
while (i != c.end())
cout << *i++ << " ";
cout << endl;
}
Output:
0 0 1 1 2 2 5
Explanation:
In this example, we have created a multiset that contains integer values. After that, we use the insert method that inserts a few values into the multiset. Next, we have executed a while loop, and the loop will execute till it reaches the end method. Inside the loop, we have printed the iterator. After that, we exit from the loop. Finally, it shows the output on the screen.
C++ Multiset end Function Example using While Loop
Let's take an example to iterate over the multiset using the while loop in C++.
Example
#include <iostream>
#include <set>
#include <string>
int main() //main function
{
using namespace std; //using standard namespace
multiset<string> mymultiset = { "Robert","Peter","Johnson","Stuart","Rozzer" };
cout<<"Elements of mymultiset are: "<<endl;
multiset<string>::const_iterator it; // declare an iterator
it = mymultiset.begin(); // assign it to the start of the multiset
while (it != mymultiset.end()) // while it hasn't reach the end
{
cout << *it << "\n";
// print the value of the element icpp tutorials to
++it; // iteration to the next element
}
cout << endl;
}
Output:
Elements of mymultiset are:
Johnson
Peter
Robert
Rozzer
Stuart
Explanation:
In the above example, we have created a multiset that contains string values and then used a for loop with an iterator to traverse it. The iteration starts from the begin function, which points to the first element, and continues until it reaches the end function, which represents the position just after the last element. The iterator is pre-incremented in each step to print all elements in sorted order. Therefore, the end function works to mark the boundary of the multiset, which returns an iterator that marks one past the last element of mymultiset.
C++ Example to find the elements using the begin and end function
Let's take a simple example where we have executed the end method on the integer values in C++.
Example
#include <iostream>
#include <string>
#include <set>
using namespace std; //using standard namespace
int main () //main function
{
int val;
multiset<int> c = {10,20,10,20,40,50};
cout<<"Enter value to find: ";
cin>>val;
auto result = c.find(val);
//find until the end of the multiset elements
if (result != c.end()) {
cout << "Element found: "<< *result;
cout << endl;
} else {
cout << "Element not found." << endl;
}
return 0;
}
Output:
Enter value to find: 60
Element not found.
Enter value to find: 20
Element found: 20
Explanation:
In the given example, we have created a multiset named c that contains several integer numbers. After that, it prompts us to enter the number that we want to find in the multiset. Next, we use the find function to check whether the element exists in the multiset or not. We use the end function that returns an iterator thacpp tutorials to the next-to-last element of the multiset.
When we enter the 60 value to find in the multiset, it compares the result with the end function, and then it prints the result as "element is not found". When we enter the value 20 to find the element, it compares this value with the end function, and it returns that the element is found.
Features of the Multiset end Function
There are several features of the multiset end function in C++. Some of the main features are as follows:
- The multiset end function is mainly utilized to return an iterator thacpp tutorials just after the last element in the multiset, not to an original element.
- When we need to call the end function on a const multiset, it returns a const_iterator. Otherwise, it will return a regular iterator.
- If we want to perform any operation or task using the multiset end function in C++, it takes only constant time, O(1), to complete those tasks.
- If we use the end function in the empty multiset, it works similarly to the begin function. If we use this function in a non-empty multiset, it marks the boundary beyond the last element of the container.
- It is commonly utilized as the upper limit in loops to traverse the complete multiset in C++.
- If we want to insert elements in the multiset container, it does not invalidate iterators to existing elements. However, it erases an element that is pointed to by an iterator and invalidates that iterator.
Conclusion
In conclusion, the multiset::end function in C++ is a simple and essential method in the multiset container. It is commonly utilized to provide an iterator that marks the boundary just beyond the last element of the multiset. We can use the end function to define iteration limits, check search results, and ensure safe traversal of elements. Although it cannot be dereferenced. It is also helpful in loop termination and iterator-based operations. Overall, the multiset end function is a simple and essential function that is used to manage and navigate a multiset efficiently.
Frequently Asked Questions
1) What is the multiset end function in C++?
The multiset::end function in C++ is a simple and essential method in the multiset container. It is commonly utilized to provide an iterator that marks the boundary just beyond the last element of the multiset.
2) What is the difference between the 'end' and 'cend' methods of C++?
The main difference between the end and cend functions in C++ is that the end method returns a non-const iterator that allows modification of the elements. On the other hand, the cend method is commonly used to return a const_iterator that ensures read-only access. Therefore, we should use the cend method for const multisets or when we do not need any modification of the elements.
3) Is it possible to use the end method with reverse iterators?
Yes, we can use the 'end' method with the reverse iterators. We can pair the 'end' method with the rbegin method thacpp tutorials to the position before the first element in reverse order.
4) Does inserting a new element change the value of the end function in C++?
Yes. When we insert the element in the multiset container, the pass-the-end iterator changes as the container grows.
5) Does erasing an element affect the iterator returned by the end function in C++?
In C++, when we erase an element from the container, it can update the internal structure, but typically the past-the-end iterator remains valid. However, the iterator thacpp tutorials to the erased element becomes invalid.
6) What happens when we call the end function on an empty multiset in C++?
In C++, when we erase an element from the container, it can update the internal structure, but typically the past-the-end iterator remains valid. However, the iterator thacpp tutorials to the erased element becomes invalid.