Question

How to calculate the percentage change between two values in C++

Answer 1

#include <iostream>

double percentage_change(double oldValue, double newValue) {
    if (oldValue == 0.0) {
        throw std::invalid_argument("oldValue cannot be zero");
    }
    
    return ((newValue - oldValue) / oldValue) * 100.0;
}

int main() {
    double oldValue = 45.0;
    double newValue = 57.0;

    try {
        double change = percentage_change(oldValue, newValue);
        std::cout << "Percentage change: " << change << "%\n";
    } catch (const std::exception& ex) {
        std::cerr << "Error: " << ex.what() << '\n';
    }

    return 0;
}



/*
run:

Percentage change: 26.6667%

*/

 

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