Correction and tips for my code

Question

I have added, modified the previous code. Now my problem is not getting the right layout. I realise arrays is better. BUT is there any way to fix it without arrays The text file is test0.txt as shown below

3 12867 1.0 2.0 1.0 5.0 4.0 5.0

5 15643 1.0 2.0 4.0 5.0 7.8 3.5 5.0 0.4 1.0 0.4

4 18674 1.0 0.4 0.4 0.4 0.4 3.6 1.0 3.6

0

The code is:

#include<stdio.h> 
   #include<stdlib.h>
   #include<math.h>
   #define MAX_POINTS 100




 double length(double x1,double x2,double y1,double y2);
 double area_bits(double x1,double x2,double y1,double y2);



int
   main(int argc,char *argv[]){
    int npoints;
    double x_point,y_point;
    double x_prev=0,y_prev=0,x_first=0,y_first=0;
    int poly_id;
    int k,l,m=0;
    
   

 double perimeter=0;
        double area=0;
        int primed=0;
    
/*Error check and echo-control*/
for(;m<=2;m++){
    
    if(m==1){
    printf("Stage 2\n");
    printf("=======\n");
    for(l=1;l<=5;l++){
        printf("+-------");
    }
    printf("+\n");
    printf("|    id |  nval | perim |  area | eccen |\n");
    for(l=1;l<=5;l++){
        printf("+-------");
    }
    printf("+\n");
    }
    if(m==0){
    printf("Stage 1\n");
    printf("======\n");
    }
while(scanf("%d %d",&npoints,&poly_id)==2){
    if(npoints>MAX_POINTS){
        printf("Exceeded limit\n");
        exit(EXIT_FAILURE);
        
    }
        if(m==0){
            printf("First polygon is %d\n",poly_id);
            printf("    x_val    y_val\n");
        
        }
        
            printf("| %5d | %5d |",poly_id,npoints);
        
        perimeter=0;
        area=0;
        for(k=0;k<npoints;k++){
            if (scanf("%lf %lf",&x_point,&y_point)==2){
            if(m==0){
            printf("%8.1f %8.1f\n",x_point,y_point);
            }
            if(k==0){
                x_first=x_point;
                y_first=y_point;
                x_prev=x_point;
                y_prev=y_point;
                
            }
            if(primed){
            perimeter+=(length(x_point,x_prev,y_point,y_prev));
            area+=area_bits(x_point,x_prev,y_point,y_prev);
            x_prev=x_point;
            y_prev=y_point;
        
            }     
            primed=1;
    }
    
}
perimeter+=length(x_first,x_prev,y_first,y_prev);
area+=area_bits(x_first,x_prev,y_first,y_prev);
if(m==0){
printf("perimeter    = %.2f m\n",perimeter);
printf("area         = %.2f m^2\n",area/2);           
printf("eccentricity = %.2f\n",( pow(perimeter,2)/(area/2))/(4*M_PI));
}

printf("%6.2f |%6.2f |%6.2f |\n",perimeter,area/2,( pow(perimeter,2)/(area/2))/(4*M_PI));                                   



}
if(m==1){
for(l=1;l<=5;l++){
        printf("+-------");
    }
    printf("+\n");

}
}
    return 0;
}

double length(double x1,double x2,double y1,double y2){
    return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
}

double area_bits(double x1,double x2,double y1,double y2){   
    return (x1-x2)*(y1+y2);
}

The goal is to assign the first column to npoints,second to poly_id and third onwards to x_point and y_point.But each row has different number of x and y coords. I have a print a table for this as well, but that I can manage.

npoints determine the number of points(eg 3 npoints give 3 x_points and y_points).

So I type in to execute:

ass_1< test0.txt

The desired output:

Stage 1
=======
First polygon is 12867
   x_val   y_val
    1.0     2.0
    1.0     5.0
    4.0     5.0
perimeter    = 10.24 m
area         =  4.50 m^2
eccentricity =  1.86

Stage 2
=======
+-------+-------+-------+-------+-------+
|    id |  nval | perim |  area | eccen |
+-------+-------+-------+-------+-------+
| 12867 |     3 | 10.24 |  4.50 |  1.86 |
| 15643 |     5 | 18.11 | 19.59 |  1.33 |
| 18674 |     4 |  7.60 |  1.92 |  2.39 |
+-------+-------+-------+-------+-------+

  

Any corrections or tips is highly appreciated. Note that I am not looking for someone to tell me the answer, just guidance.

Thank You!

Answer 1

Two problems:

1) You should put some kind of delimiter (e.g. "\n") in your printf

2) Your counter should be for(i=0; i < npoints; i++)

Modified code:

#include<stdio.h> 
#include<stdlib.h>

int
main(int argc,char *argv[]){
  int npoints,poly_id;
  double x_point,y_point;
  int i;

  while(scanf("%d %d",&npoints,&poly_id)==2){
    for(i=0; i < npoints; i++){
      scanf("%lf %lf",&x_point,&y_point);
      printf("%f %f\n",x_point,y_point);
    }
    printf("\n");
  }
  return 0;
}

Output:

3 12867 1.0 2.0 1.0 5.0 4.0 5.0
1.000000 2.000000
1.000000 5.000000
4.000000 5.000000