C++ Math llround()

long long int llround(data_type x);

#include <iostream>
#include<math.h>
using namespace std;
int main()
{
    float x=50.8;
    std::cout <<"The value of x is :" <<x<< std::endl;
    std::cout << "The rounded value of x is :"<<llround(x) << std::endl;
    return 0;
}

The value of x is :50.8
The rounded value of x is :51