C++ Basics: How to Determine a Triangle Type Using IF-ELSE Statements

A classic problem when learning C++ is checking what type of triangle you have based on 3 sides given by the user. Let's see how to write this logic cleanly using if-else structures without nesting too many conditions.

#include <iostream>
using namespace std;

int main() {
    double a, b, c;
    cout << "Enter three sides of the triangle: ";
    cin >> a >> b >> c;

    // Check if the sides can actually form a triangle
    if (a + b > c && a + c > b && b + c > a) {
        if (a == b && b == c) {
            cout << "The triangle is Equilateral" << '\n';
        }
        else if (a == b || b == c || a == c) {
            cout << "The triangle is Isosceles" << '\n';
        }
        else {
            cout << "The triangle is Scalene" << '\n';
        }
    } else {
        cout << "These sides cannot form a valid triangle" << '\n';
    }

    return 0;
}