Bjarne Stroustrup “Programming Principles and Practice Using C++” Chapter 4 Drill 10
Using std_lib_facilities.h by Bjarne Stroustrup.

// Philipp Siedler
// Bjarne Stroustrup's PP
// Chapter 4 Drill 10
#include "std_lib_facilities.h"
int main()
{
cout << "Enter a double followed by m(meter) in(inch) ft(feet) or cm(centimeter or a '|' to terminate the program:\n";
vector<double> numbers;
vector<double> numbersMeter;
double x;
double y;
string unit;
while (cin >> x >> unit)
{
if (unit == "m")
{
y = x;
numbersMeter.push_back(x);
}
else if (unit == "in")
{
y = (x * 2.54) / 100;
}
else if (unit == "ft")
{
y = ((x / 12)*2.54) / 100;
}
else if (unit == "cm")
{
y = x / 100;
}
else
{
cout << "I dont know what " << unit << " for a unit is, enter a valid unit \n";
continue;
}
cout << "you entered: " << x << " " << unit << "\n\n";
numbers.push_back(y);
double sum = 0;
for (int i = 0; i < numbers.size(); i++)
{
sum += numbers[i];
}
cout << "the sum of all numbers in m is: " << sum << " m\n";
sort(numbers);
cout << "the smallest so far is: " << numbers[0] << " " << "m\n";
cout << "the largest so far is: " << numbers[numbers.size() - 1] << " " << "m\n";
cout << "you have entered: " << numbers.size() << " values\n";
cout << "all the values entered as meters: \n";
for (int i = 0; i < numbersMeter.size(); i++)
{
cout << numbersMeter[i] << "\n";
}
}
}

Output:
Enter a double followed by m(meter) in(inch) ft(feet) or cm(centimeter or a '|' to terminate the program:
1.2 ft
you entered: 1.2 ft
the sum of all numbers in m is: 0.00254 m
the smallest so far is: 0.00254 m
the largest so far is: 0.00254 m
you have entered: 1 values
all the values entered as meters:
2.3 m
you entered: 2.3 m
the sum of all numbers in m is: 2.30254 m
the smallest so far is: 0.00254 m
the largest so far is: 2.3 m
you have entered: 2 values
all the values entered as meters:
2.3
4.5 m
you entered: 4.5 m
the sum of all numbers in m is: 6.80254 m
the smallest so far is: 0.00254 m
the largest so far is: 4.5 m
you have entered: 3 values
all the values entered as meters:
2.3
4.5