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# multiset clear() function in C++ STL

The multiset::clear() function is a built-in function in C++ STL which removes all elements from the multiset container. The final size of multiset container after removal is 0.

Syntax:

`multiset_name.clear()`

Parameters: The function does not accept any parameter.
Return Value: The function does not returns anything.

Below programs illustrates the multiset::clear() function:

Program 1:

## C++

 `// C++ program to demonstrate the``// multiset::clear() function``#include ``using` `namespace` `std;``int` `main()``{` `    ``int` `arr[] = { 15, 10, 15, 11, 10 };` `    ``// initializes the set from an array``    ``multiset<``int``> s(arr, arr + 5);` `    ``// prints all elements in set``    ``cout << ``"The elements in multiset are: "``;``    ``for` `(``auto` `it = s.begin(); it != s.end(); it++)``        ``cout << *it << ``" "``;` `    ``cout << ``"\nThe size after clear() is: "``;` `    ``// erases all elements``    ``s.clear();``    ``cout << s.size();` `    ``return` `0;``}`

Output:

```The elements in multiset are: 10 10 11 15 15
The size after clear() is: 0```

Time Complexity: O(N), where N is the total number of elements present in the multiset.
Auxiliary Space: O(N)

Program 2:

## C++

 `// C++ program to demonstrate the``// multiset::clear() function``#include ``using` `namespace` `std;``int` `main()``{` `    ``int` `arr[] = { 15, 10, 15, 11, 10, 18, 18, 20, 20 };` `    ``// initializes the set from an array``    ``multiset<``int``> s(arr, arr + 9);` `    ``// prints all elements in set``    ``cout << ``"The elements in multiset are: "``;``    ``for` `(``auto` `it = s.begin(); it != s.end(); it++)``        ``cout << *it << ``" "``;` `    ``cout << ``"\nThe size after clear() is: "``;` `    ``// erases all elements``    ``s.clear();``    ``cout << s.size();` `    ``return` `0;``}`

Output:

```The elements in multiset are: 10 10 11 15 15 18 18 20 20
The size after clear() is: 0```

Time Complexity: O(N), where N is the total number of elements present in the multiset.
Auxiliary Space: O(N)

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