Example: Triangle Measurement in C

// Triangle Measurement
#include <stdio.h>
#include <math.h> // Required for sqrt()

void calculateTriangle() {
    float side1, side2, side3, perimeter, semiPerimeter, area;

    printf("\n--- Triangle Calculator ---\n");
    printf("Enter the length of side 1: ");
    scanf("%f", &side1);
    printf("Enter the length of side 2: ");
    scanf("%f", &side2);
    printf("Enter the length of side 3: ");
    scanf("%f", &side3);

    if (side1 <= 0 || side2 <= 0 || side3 <= 0) {
        printf("Error: Side lengths must be positive values.\n");
        return;
    }

    // Triangle inequality theorem check
    if (!((side1 + side2 > side3) && (side1 + side3 > side2) && (side2 + side3 > side1))) {
        printf("Error: The given side lengths do not form a valid triangle.\n");
        return;
    }

    perimeter = side1 + side2 + side3;
    semiPerimeter = perimeter / 2;
    
    // Heron's formula for area
    area = sqrt(semiPerimeter * (semiPerimeter - side1) * (semiPerimeter - side2) * (semiPerimeter - side3));

    printf("Perimeter of the triangle: %.2f\n", perimeter);
    printf("Area of the triangle: %.2f\n", area);
}