Auto Modifier in C++

Program 1

// auto modifier in cpp
#include<iostream>
using namespace std;
int main()
{
    system("cls");
     int a{10};
     a=800;
    cout<<a;
    //   auto a=123.78f;
    //   cout<<sizeof(a) <<"  "<<a;
    //   a=12;
    //   cout<<"\n"<<sizeof(a)<< "  "<<a;
    return 0;
}