using c++ to implement a class of trian gle

Sure, to implement a class of triangle using C, you can define a struct for the triangle with three sides as its properties. Then, you can write functions for calculating the perimeter, area or any other operations you need. Here's an example code:

#include <stdio.h>
#include <math.h>

struct Triangle {
    double side1;
    double side2;
    double side3;
};

double calculatePerimeter(struct Triangle t) {
    return t.side1 + t.side2 + t.side3;
}

double calculateArea(struct Triangle t) {
    double p = calculatePerimeter(t) / 2.0;
    return sqrt(p * (p - t.side1) * (p - t.side2) * (p - t.side3));
}

int main() {
    struct Triangle t1 = { 3.0, 4.0, 5.0 };
    printf("Perimeter of triangle t1 = %.2lf\n", calculatePerimeter(t1));
    printf("Area of triangle t1 = %.2lf\n", calculateArea(t1));
    return 0;
}

Please note that this is just an example implementation and there may be other ways to implement a class of triangle in C.