/* June 08, 1998 */
/* Program to compute the area of triangle or square using pointers*/

#include 
#include 

/* function definition */
void area_triangle (double tbase, double theight, double *tareap);
void area_square (double sside, double *sareap);

main ()
{
	/* declarations */
	double side, base, height, tarea, sarea;
	char type;

	/* Request for type */
	printf("Enter S for Square or T for Triangle> ");
	scanf("%c", &type);
	
	/* condition statements */
	if (type == 'T' || type == 't')
	{
	/* Get input */
	printf("Input the length of the base of the triangle> ");
	scanf("%lf", &base);	
	printf("Input the length of the height of the triangle> ");
	scanf("%lf", &height);


	area_triangle(base, height, &tarea);

	/* display area of triangle */
	printf("The area of the triangle is %.2f\n", tarea);
	}
	else
	{
	/* Get input */
	printf("Input the length of the side of the square> ");
	scanf("%lf", &side);	

	area_square(side, &sarea);
	
	/* display area of square */
	printf("Area of the square is %.2f\n", sarea);
	}	
}


/* function definition */

void
area_triangle(double tbase, double theight, double *tareap)
{

	/* compute area of triangle */	
	*tareap = 0.5 * (tbase) * (theight);
}

void
area_square(double sside, double *sareap)
{
	/* compute area of square */
	*sareap = (sside) * (sside);
}

    Source: geocities.com/yosemite/rapids/9568

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