#include <iostream>
#include<string.h>
#include<stdio.h>
using namespace std;
int main(){
// comment can be writen starting with "//"
  double x;
  double min=0;
  double max=5;
  double step=0.5;
  char c1[16]="Hello";
  char c2[64];
  cout << c1 << endl;
  x=min;
  while(x<max){
    sprintf(c2,"%s_%.1lf.dat",c1,x);
    //sprintf can have more than one paramters
    cout << "x:"<<x<<"\tc2:"<<c2<<endl;
    x+=step;
  }
  return 0;
}