C++ multiset find
The find function in C++ multiset is employed to search for an element with a specified value val. In case the element is located, it will provide an iterator pointing to that element; otherwise, it will return an iterator pointing to the end of the multiset, which is multiset::end.
Syntax
iterator find (const value_type& val) const; // until C++ 11
const_iterator find (const value_type& val) const; //since C++ 11
iterator find (const value_type& val); //since C++ 11
Parameter
val : denotes the specific value that will be sought in the multiset data structure.
Return value
If the element is located, it will return an iterator that points to the element. In case the element is not found, it will return an iterator pointing to the end of the multiset, which is referred to as multiset::end.
Complexity
Logarithmic in size.
Iterator validity
No changes.
Data Races
The container is accessed without making any modifications to it, whether it is the constant or non-constant versions being used.
Accessing and modifying elements concurrently is considered safe when there are no mapped values being accessed.
Exception Safety
If an error is raised, the multiset container remains unaltered.
Example 1
Let's examine a straightforward example of locating the element with the specified key value:
#include <iostream>
#include <set>
using namespace std;
int main(void) {
multiset<int> m = {100,200,300,300};
auto it = m.find(300);
cout << "Iterator points to " << *it << endl;
return 0;
}
Output:
Iterator points to 300
Example 2
Let's see a simple example to find the element:
#include <iostream>
#include <set>
using namespace std;
int main(void) {
multiset<char> m = {'a', 'b', 'c', 'a'};
auto it = m.find('e');
if ( it == m.end() ) {
// not found
cout<<"Element not found";
}
else {
// found
cout << "Iterator points to " << *it<< endl;
}
return 0;
}
Output:
Element not found
The find method searches for the key value "e" within the multiset "m". If the key is not present in the multiset, it will return a message indicating that the key was not found. Otherwise, it will display the contents of the multiset.
Example 3
Let's see a simple example:
#include <iostream>
#include <set>
using namespace std;
int main()
{
char n;
multiset<char> example = {'a','b','c','d','b'};
cout<<"Enter the element which you want to search: ";
cin>>n;
auto search = example.find(n);
if (search != example.end()) {
cout << n<<" found and the value is " << *search << '\n';
} else {
cout << n<<" not found\n";
}
}
Output:
Enter the element which you want to search: b
b found and the value is b
In the previous example, the find method is utilized to locate the element based on the value provided by the user.
Example 4
Let's see a simple example:
#include <iostream>
#include <set>
using namespace std;
int main () {
multiset<int> mymultiset;
multiset<int>::iterator it;
for (int i = 1; i <= 10; i++) mymultiset.insert(i*10);
it = mymultiset.find(40);
mymultiset.erase (it);
mymultiset.erase (mymultiset.find(60));
cout << "mymultiset contains:";
for (it = mymultiset.begin(); it!=mymultiset.end(); ++it)
cout << ' ' << *it;
cout << '\n';
return 0;
}
Output:
mymultiset contains: 10 20 30 50 70 80 90 100
