C++ Set Library - set() Function

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Description

The C++ constructor std::set::set() (Initializer-List Constructor) constructs a set container with the contents of the initializer list init

Declaration

Following is the declaration for std::set::set() Initializer-list constructor from std::set header.

C++11

set (initializer_list<value_type> init,
     const key_compare& comp = key_compare(),
     const allocator_type& alloc = allocator_type());

C++14

set (initializer_list<value_type> init,
     const key_compare& comp = key_compare(),
     const allocator_type& alloc = allocator_type());
set (initializer_list<value_type> init,
     const allocator_type& alloc = allocator_type());

Parameters

• alloc − Input iterator to initial position.

• comp − comparison function object to use for all comparisons of keys

• init − init is a initializer_list object which initializes the set container elements. Elements present in the set container are of value_type (Member Type)

Return value

Constructor never returns any value.

Exceptions

This member function has no effect in case any exception is thrown.

Time complexity

N log(N) in general, where N = init.size();

else, linear in N, i.e., O(N) if init is already sorted.

Example

The following example shows the usage of std::set::set() (initializer_list) constructor.

#include <iostream>
#include <set>
#include <string>

using namespace std;

int main() {
   // Initializer list constructor
   std::set<std::string> fruit {
      "orange", "apple", "mango", "peach", "grape"
   };

   std::cout << "Size of set container fruit is : " << fruit.size();
   return 0;
}

Let us compile and run the above program, this will produce the following result −

Size of set container fruit is : 5