The ‘=’ is an operator in C++ STL which copies (or moves) a set to another set and set::operator= is the corresponding operator function. There are three versions of this function:
- The first version takes reference of an set as an argument and copies it to an set.
Syntax:
ums1.operator=(set &set2)
Parameters: The first version takes the reference of an set as argument.
- The second version performs a move assignment i.e it moves the content of an set to another set.
Syntax:
ums1.operator=(set &&set2)
Parameters: The second version takes the r-value reference of an set as argument
- The third version assigns contents of an initializer list to an set.
Syntax:
ums1.operator=(initializer list)
Parameters: The third version takes an initializer list as argument.
Return Value: All of them return the value of this pointer(*this).
The following programs illustrates set::operator= :
// C++ code to illustrate the method // set::operator=() #include <iostream> #include <set> using namespace std;
// merge function template < class T>
T merge(T a, T b) { T t(a);
t.insert(b.begin(), b.end());
return t;
} int main()
{ set< int > sample1, sample2, sample3;
// List initialization
sample1 = { 1, 2, 3, 4, 5 };
sample2 = { 6, 7, 8, 1 };
// Merge both sets and
// move the result to sample3
sample3 = merge(sample1, sample2);
// copy assignment
sample1 = sample3;
// Print the sets
for ( auto it = sample1.begin(); it != sample1.end(); ++it) {
cout << *it << " " ;
}
cout << endl;
for ( auto it = sample2.begin(); it != sample2.end(); ++it) {
cout << *it << " " ;
}
cout << endl;
for ( auto it = sample3.begin(); it != sample3.end(); ++it) {
cout << *it << " " ;
}
cout << endl;
return 0;
} |
Output:
1 2 3 4 5 6 7 8 1 6 7 8 1 2 3 4 5 6 7 8