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C++ - SET

A set is a Collection that can also hold multiple values. And elements in a set are sorted and doesn't allow duplicate values.

A set is created in the same way a List is created.

set<string> x;

The above set is used to hold values of string type.

Creating an empty set

Example :

#include <iostream>
#include <set>

using namespace std;

int main() {
        
    set<string> x; 
        
    x.insert("Tom");
    x.insert("John");
    x.insert("C++");
        
    for (string data : x)  
    {  
        cout << data << endl;  
    }
        
    return 0;    
}

Output :

C++
John
Tom

In order to use set in your code, the first thing you need to dos is, include Set in your code.

#include <set>

So, in the above code, we have declared an empty set that is used to hold values of string data type.

set<string> x;

Then we have used the insert() method to add the values to the set.

x.insert("Tom");
x.insert("John");
x.insert("C++");

And finally, used the for loop to print the contents of the set.

for (string data : x)
{
	cout << data << endl;
}

Elements in a Set are sorted

Now, if you look at the above output,

Output :

C++
John
Tom

The elements are printed in Sorted order(i.e. Ascending order). That is because the elements in a Set are stored in soted order.

Set doesn't accept duplicates

Example :

#include <iostream>
#include <set>

using namespace std;


int main() {
        
    set<string> x; 
        
    x.insert("Tom");
    x.insert("John");
    x.insert("C++");
    x.insert("John");
        
    for (string data : x)  
    {  
        cout << data << endl;  
    }
        
    return 0;    
}

Output :

C++
John
Tom

So, in the above code we have created a set using the values, "Tom", "John", "C++" and "John".

set<string> x;

Now, if we see the output,

Output :

C++
John
Tom

You can see only three values are printed.

This is because in the above set, the name John is present twice.

And since a set doesn't accept duplicates, the name John is not inserted to the set twice.

And we see the above output with John present only once.

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