#include <iostream>
#include <cmath>
#include <iomanip>
double percentChange(double x, double y) {
return ((y - x) / std::fabs(x)) * 100.0;
}
std::string describeChange(double x, double y) {
double pct = percentChange(x, y);
std::ostringstream out;
out << std::fixed << std::setprecision(2);
if (pct > 0) {
out << "From " << std::setprecision(1) << x
<< " to " << y
<< std::setprecision(2)
<< " is a " << pct << "% increase (+" << pct << "%)";
} else if (pct < 0) {
out << "From " << std::setprecision(1) << x
<< " to " << y
<< std::setprecision(2)
<< " is a " << std::fabs(pct) << "% decrease (" << pct << "%)";
} else {
out << "From " << std::setprecision(1) << x
<< " to " << y
<< " is no change";
}
return out.str();
}
int main() {
std::cout << describeChange(-80.0, 120.0) << "\n";
std::cout << describeChange(120.0, 30.0) << "\n";
}
/*
run:
From -80.0 to 120.0 is a 250.00% increase (+250.00%)
From 120.0 to 30.0 is a 75.00% decrease (-75.00%)
*/
