# set lower_bound() function in C++ STL

C++Server Side ProgrammingProgramming

Set lower_bound() function in C++ STL returns an iterator pointing to the element in the container which is equivalent to k passed in the parameter. If k is not present in the set container, then the function returns an iterator pointing to the immediate next element which is just greater than k.

## Algorithm

Begin
Initialize an empty set container s.
Initializing a set container as inetrator.
Insert some elements in s set container.
Call function to find the lower bound value of a given key, which is
passed to iter set container.
Print the lower bound value of the given key.
End.

## Example Code

Live Demo

#include<iostream>
#include <bits/stdc++.h>
using namespace std;
int main()
{
set<int> s;                 //Declaring an empty set container
set<int>::iterator iter;    //Declaring a set container as iterator which will point to the lower bound value
s.insert(7);                //inserting elements in the set container s
s.insert(6);
s.insert(1);
s.insert(4);
s.insert(2);
s.insert(9);
s.insert(10);
iter = s.lower_bound(4);       //passing a key by parameter to find its lower bound
cout <<"The lower bound of 4 is: "<< *iter << " "<<endl; //printing the lowerbound value
iter = s.lower_bound(5);
cout <<"The lower bound of 5 is: " <<*iter << " "<<endl;
iter = s.lower_bound(30);
cout <<"The lower bound of 30 is: " <<*iter << " "<<endl;

return 0;
}

## Output

The lower bound of 4 is: 4
The lower bound of 5 is: 6
The lower bound of 30 is: 7
Updated on 30-Jul-2019 22:30:25