set operator= in C++ STL

The function operator= is used in sets to copy one set (or move to another in C++ STL. It behaves as a normal ‘=’ assignment operation for sets. There are there overloaded forms of this function −

• copy :- set& operator= (const set& s1) −

  This function copies all the elements in set s1 to another set. The parameter passed is set of the same type.

• Usage − set s1=s2;

• move :- set& operator=( set &&s1 ) −

  This moves the elements of set s1 into the calling set.

• Initializer list :- set& operator= (initializer_list<value_type> ilist) −

  This version copies the values of the initializer list ilist into the calling set.

  Usage − set<int> s1= { 1,2,3,4,5 };

Note − All of them return the reference of this pointer of set<T> type.

Following program is used to demonstrate the usage of round function in a C++ program −

Example

 Live Demo

#include <iostream> #include <set> using namespace std; // merge function int main(){    set<int> set1, set2;    // List initialization    set1 = { 1, 2, 3, 4, 5 };    set2 = { 10,11,12,13 };    // before copy    cout<<"set1 :";    for (auto s = set1.begin(); s != set1.end(); ++s) {       cout << *s << " ";    }    cout << endl;    cout<<"set2 :";    for (auto s = set2.begin(); s != set2.end(); ++s) {       cout << *s << " ";    }    //after copy set1 to set2    cout<<endl<<"After Copy"<<endl;    cout<<"set1 :";    set1=set2;    for (auto s = set1.begin(); s != set1.end(); ++s) {       cout << *s << " ";    }    return 0; }

Output

set1 :1 2 3 4 5 set2 :10 11 12 13 After Copy set1 :10 11 12 13