C++ set swap() Function

C++ set swap() Function with tutorial for beginners and professionals with examples on constructor, destructor, operator=(), begin(), cbegin(), cend(), end(), crbegin(), empty(), max_size(), clear(), emplace_hint(), key_comp(), swap() etc.

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C++ set swap()

C++ swap() function is used to swap (or exchange) the content of two sets but both the sets must be of same type although sizes may differ.

Syntax

void swap (set& x);

Parameter

x: set container to exchange the contents with.

Return value

None

Complexity

Constant.

Iterator validity

All references, iterators and pointers referring to elements in both set containers remain valid, but now are referring to elements in the other set container, and iterate in it.

Data Races

Both the container and x are modified.

Exception Safety

No effect on container if exception is thrown.

Example 1

Let's see the simple example to swap the element of one set to another:

#include <iostream>
#include <set>

using namespace std;

int main(void) {
   set<int> m1 = {1,2,3,4,5};


   set<int> m2;

   m2.swap(m1);

   cout << "Set contains following elements" << endl;

   for (auto it = m2.begin(); it != m2.end(); ++it)
      cout << *it<< endl;

   return 0;
}

Output:

Set contains following elements
1
2
3
4
5

In the above example, set m1 has five elements and m2 is empty. When you swap m1 to m2 then all the elements of m1 is swapped to m2.

Example 2

Let's see a simple example to exchange the content of two sets:

#include <iostream>
#include <set>

using namespace std;

 int main () {
   int myints[] = {10,20,30,40,50,60};
   set<int> first (myints,myints+3);
   set<int> second (myints+3,myints+6);  

   first.swap(second);

   cout << "first set contains:";
   for (set<int>::iterator it = first.begin(); it!=first.end(); ++it)
      cout << ' ' << *it;
   cout << '\n';

   cout << "second set contains:";
   for (set<int>::iterator it = second.begin(); it!=second.end(); ++it)
      cout << ' ' << *it;
   cout << '\n';

   return 0;
}

Output:

first set contains: 40 50 60
second set contains: 10 20 30

Example 3

Let's see a simple example to swap the contents of two sets:

#include<iostream>
#include<set>
using namespace std;
 
int main()
{
    // Take any two sets
    set<char> set1, set2;
    
    set1 = {'a','b','c','d'}; 
    set2 = {'x','y','z'};
 
    // Swap elements of sets
    swap(set1, set2);
 
    // Print the elements of sets
    cout << "set1:\n";
    for (auto it = set1.begin(); it != set1.end(); it++)
        cout << "\t" << *it<< '\n';
 
    cout << "set2:\n";
    for (auto it = set2.begin(); it != set2.end(); it++)
        cout << "\t" << *it<< '\n';
 
    return 0;
}

Output:

set1:
	x
	y
	z
set2:
	a
	b
	c
	d

In the above example, another form of swap() function is used to swap the contents of two sets.

Example 4

Let's see a simple example:

#include <set>  
#include <iostream>  
  
int main( )  
{  
   using namespace std;  
   set <int> s1, s2, s3;  
   set <int>::iterator s1_Iter;  
  
   s1.insert( 10 );  
   s1.insert( 20 );  
   s1.insert( 30 );  
   s2.insert( 100 );  
   s2.insert( 200 );  
   s3.insert( 300 );  
  
   cout << "The original set s1 is:";  
   for ( s1_Iter = s1.begin( ); s1_Iter != s1.end( ); s1_Iter++ )  
      cout << " " << *s1_Iter;  
   cout   << "." << endl;  
  
   // This is the member function version of swap  
   s1.swap( s2 );  
  
   cout << "After swapping with s2, list s1 is:";  
   for ( s1_Iter = s1.begin( ); s1_Iter != s1.end( ); s1_Iter++ )  
      cout << " " << *s1_Iter;  
   cout  << "." << endl;  
  
   // This is the specialized template version of swap  
   swap( s1, s3 );  
  
   cout << "After swapping with s3, list s1 is:";  
   for ( s1_Iter = s1.begin( ); s1_Iter != s1.end( ); s1_Iter++ )  
      cout << " " << *s1_Iter;  
   cout   << "." << endl;  
}

Output:

The original set s1 is: 10 20 30.
After swapping with s2, list s1 is: 100 200.
After swapping with s3, list s1 is: 300.

Next TopicSet clear() Function

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C++ set swap() Function

C++ set swap()

Syntax

Parameter

Return value

Complexity

Iterator validity

Data Races

Exception Safety

Example 1

Example 2

Example 3

Example 4

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.Net

Java

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