Bjarne Stroustrup “Programming Principles and Practice Using C++” Chapter 4 Drill 4
Using std_lib_facilities.h by Bjarne Stroustrup.

// Philipp Siedler
// Bjarne Stroustrup's PP
// Chapter 4 Drill 4
#include "std_lib_facilities.h"
int main()
{
cout << "type in two doubles or a '|' to terminate the program:\n";
double x1;
double x2;
while (cin >> x1 >> x2)
{
if (x1 < x2){
cout << "the smaller number is x1: " << x1 << "\n";
cout << "the larger number is x2: " << x2 << "\n";
}
else if (x1 == x2){
cout << "the numbers are equal" << "\n";
}
else{
cout << "the larger number is x1: " << x1 << "\n";
cout << "the smaller number is x2: " << x2 << "\n";
}
}
return 0;
}

Output 1:
type in two doubles or a '|' to terminate the program:
2.3 4.5
the smaller number is x1: 2.3
the larger number is x2: 4.5