i need advice on how to write functions

[jcorral79]

I have to write a program that calculates the perimeter, semiperimeter, area and centroid of a triangle using coordinates input by user. Some of the requirements for the program are: "write 2 functions which have 6 parameters (x and y values of each of the points) and compute the area and perimeter of triangle. write 2 functions which have 3 parameters and compute the x and y values of the centroid." I have written a function that computes the side of a triangle which is:

/*programming assignment 2*/

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

double distance(double x1, double y1, double x2, double y2);


int main(void)
{
double point1, point2, point3, point4, point5, point6;

printf("Enter coordinates of point A (x y):");
scanf("%lf%lf", &point1, &point2);
printf("Enter coordinates of point B (x y):");
scanf("%lf%lf", &point3, &point4);
printf("Enter coordinates of point C (x y):");
scanf("%lf%lf", &point5, &point6);

return 0;

}

double distance(double x1, double y1, double x2, double y2)

{
double side1, side2;

side1 = pow((x2-x1),2) + pow((y2-y1),2);

side2 = sqrt(side1);

return side2;

}



My first question is: How do I use the values returned in the distance function in another function to determine perimeter. And after that, use the values from the perimeter function to determine area in the area function.

My second question is: How do print the coordinates the user input in parentheses? For example user inputs 3,4 as coordiantes for point A. My output has to be "Point A = (3.000, 4.000). I forgot to mention that this program has to be written in C and not C++

Any help would be greatly appreciated!!!

[sanzilla]

since you are using the C programming language , however
it is bettter to use like this

struct pointer 
{
     int x ;
     int y
} point1 , point2 , point3 ;

Then your distance function will only takes two arguments.

double distance ( pointer pt1 , pointer pt2 ){
 ...
}

Then the things will be more clear to you. And even you can make a struct
to the trangle.

struct trangle {
pointer pt1 ;
pointer pt2 ;
pointer pt3 ;

double calculate_perimeter()
{
//....
}
};

even in the C programming language you can use object oriented approaches. So use it.

[jcorral79]

Thanks for your advice. I won't be able to use the STRUCT feature/function because we have not learned that in class yet. We have to use functions. Do you know how I would use the values from my distance function in another function to calculate the perimeter?? Again, thanks for all your help.

[Scipio]

You can use global variables or pointers (if you have learned about pointers)