C++ set max_size
C++ max_size function is used to get the maximum number of size a set container can hold.
Syntax
Member type size_type is an unsigned integral type.
size_type max_size() const; // until C++ 11
size_type max_size() const noexcept; //since C++ 11
Parameter
Return value
It returns the maximum allowed length of the set container.
Complexity
Constant.
Iterator validity
No changes.
Data Races
The container is accessed.
Concurrently accessing the elements of a set is safe.
Exception Safety
This member function never throws exception.
Example 1
Let's see the simple example to calculate the maximum size of the set:
#include <iostream>
#include <set>
using namespace std;
int main()
{
set<char,char> s;
cout << "Maximum size of a 'set' is " << s.max_size() << "\n";
return 0;
}
Output:
Maximum size of a 'set' is 461168601842738790
In the above example, max_size function returns the maximum size of the set.
Example 2
Let's see a simple example:
#include <iostream>
#include <set>
using namespace std;
int main ()
{
int i;
set<int> myset;
if (myset.max_size()>1000)
{
for (i=0; i<1000; i++) myset.insert(0);
cout << "The set contains 1000 elements.\n";
}
else cout << "The set could not hold 1000 elements.\n";
return 0;
}
Output:
The set contains 1000 elements.
In the above example, member max_size is used to check beforehand whether the set will allow for 1000 elements to be inserted.
Example 3
Let's see a simple example to find the max size of an empty set and a non-empty set:
#include <set>
#include <iostream>
using namespace std;
int main()
{
// initialize container
set<int> mp1, mp2;
mp1 = {1111};
// max size of Non-empty set
cout << "The max size of mp1 is " << mp1.max_size();
// max size of Empty-set
cout << "\nThe max size of mp2 is " << mp2.max_size();
return 0;
}
Output:
The max size of mp1 is 461168601842738790
The max size of mp2 is 461168601842738790
In the above example, there are two sets i.e. m1 and m2. m1 is a non-empty set and m2 is an empty set. But the maximum size of both sets is the same.
Example 4
Let's see a simple example:
#include <iostream>
#include <set>
#include <string>
using namespace std;
int main() {
typedef set<string> city;
string name;
city fmly ;
int n;
cout<<"Enter the number of family members :";
cin>>n;
cout<<"Enter the name of each member: \n";
for(int i =0; i<n; i++)
{
cin>> name; // Get key
fmly.insert(name); // Put them in set
}
cout<<"\nTotal number of population of city set: "<<fmly.max_size();
cout<<"\nTotal member of family is:"<< fmly.size();
cout<<"\nName of family members: \n";
cout<<"\nName \n ________________________\n";
city::iterator p;
for(p = fmly.begin(); p!=fmly.end(); p++)
{
cout<<(*p)<<" \n ";
}
return 0;
}
Output:
Enter the number of family members: 5
Enter the name of each member:
Aman
Nikita
Divya
Amita
Kashish
Total number of population of city set: 461168601842738790
Total member of family is:5
Name of family members:
Name
________________________
Aman
Amita
Divya
Kashish
Nikita
In the above example, the program first creates city set interactively with given number of size. Then it displays the total size a city set can contain, total size of a fmly and all the names and their age available in the set.