You are to modify the program below so that after inputting a polygon and comput

Question

 You are to modify the program  below so that after inputting a polygon and computing and displaying the area, the program will read an arbitrary number of points and determine if each one is inside or outside the polygon. Again a non-numeric indicates the end of this list of points. See sample output 2. Your program must have a function with header: int ptInPoly(Point q, Point p[], int n) that determines if point q is in the polygon given in p. The points in p are in clockwise order. ptInPoly is called from your main function for each point to be checked for inclusion in a polygon. Your functions returns 1 if the point is inside the polygon and 0 if it is not. A point on the boundary is considered to be inside the polygon.   #include <stdio.h> #include <stdlib.h>  typedef struct {         double x, y; } Point;  double parea(Point p[], int n) { // Finds area of a polygon given as n points // in clockwise order around the polygon. // Does not matter which point is first.         int i, j = n - 1;  // j starts at last point         double area = 0.0;         for (i = 0; i < n; i++) {                 area += (p[i].x - p[j].x) * (p[i].y + p[j].y); // divide by 2 done once                 j = i;         }         return area / 2.0; }  int main(void) {         Point poly[100];         int n;         char str[10];         setvbuf(stdout, NULL, _IONBF, 0);          while (1) {                 printf("Enter polygon points in clockwise direction: ");                 n=0;                 while (1) {                         if(2>scanf("%lf%lf",&poly[n].x,&poly[n].y)){                                 scanf("%s",str); // this clears the nonnumeric from the input                                 break;                         }                         n++;                 }                 if (n == 0)                         break;                 printf("Area= %f ", parea(poly, n));         }         printf("Program completed normally. ");         return EXIT_SUCCESS; } 

Explanation / Answer

#include #include typedef struct { double x, y; } Point; double parea(Point p[], int n) { // Finds area of a polygon given as n points // in clockwise order around the polygon. // Does not matter which point is first. int i, j = n - 1; // j starts at last point double area = 0.0; for (i = 0; i scanf("%lf%lf",&poly[n].x,&poly[n].y)){ scanf("%s",str); // this clears the nonnumeric from the input break; } n++; } if (n == 0) break; printf("Area= %f ", parea(poly, n)); } printf("Program completed normally. "); return EXIT_SUCCESS; }

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