using FSCANF to read mixed text/double files

Hi there,

I am trying to read a file that is only partly sequential; it contains strings between "arrays" of ints and arrays of doubles of different sizes.

The file is reported below. Although I could read it by a combination of fgets() and strtok() calls, I am trying to change my old way to read it into a more efficient and shorter way by using fscanf throughout.

The problem is that, from the way I wrote the algorithm, it apparently stops reading the file correctly once it reaches the intermediate strings END_ELEMENTS and COORDINATES (See below).

I believe that I am doing somethign wrong in the sequence of calling fscanf, but I can't understand why.

I hope someone can help with this. I am sure it is a common task to read mixed files.
I use programming for my work but I am not actually a programmer, so that reading files is at times tricky

Thank you in advance:

1) File to be read

Code:

---

ELEMENTS 
          1          2        4        3        1 
          2          5        7        4        2 
          3          4        8        6        3 
          4          7        9        8        4 
END_ELEMENTS 
COORDINATES 
          1  0.000000 10.000000   
          2  0.000000 5.000000   
          3  5.000000 10.000000   
          4  5.000000 5.000000   
          5  0.000000 0.000000   
          6  10.000000 10.000000   
          7  5.000000 0.000000   
          8  10.000000 5.000000   
          9  10.000000 0.000000   
END_COORDINATES

---

2) My function that does that:

Code:

---

        //Testing the code:
       
        int nnodes = 9;
        int nelem = 4;
       
        char header[32];
        int        CONN[nelem][4];
        double COORDS[nnodes][3];
       
       
        //READ the FIRST LINE OF THE FILE:  ELEMENTS
                fscanf(msh_file_ID, "%s\n", header);
                printf("%s\t\n", header);
                k = 1;
                i = 0;

                while( !feof(msh_file_ID)){
                        if(k <= nelem){
                        //Read CONN:
                                fscanf(msh_file_ID, "%d %d %d %d %d\n", &(CONN[k][0]), &(CONN[k][1]), &(CONN[k][2]), &(CONN[k][3]), &(CONN[k][4]) );
                               
                                printf(" %d %d %d %d %d\n ", CONN[k][0], CONN[k][1], CONN[k][2], CONN[k][3], CONN[k][4] );
                        }
                        //Read the intermediate strings: "END_ELEMENTS" and "COORDINATES"
                        else if(k > nelem && k <= nelem+2){
                                //String END_ELEMENTS
                                fscanf(msh_file_ID, "%s\n", header);
                                        printf("%s\t\n", header);
                                //String COORDINATES
                                fscanf(msh_file_ID, "%s\n", header);
                                        printf("%s\t\n", header);
                        }
                        //Read COORDS
                        else if(k > nelem+2 && k <= nelem+2+nnodes){
                                fscanf(msh_file_ID, "%f %f %f", &COORDS[i][0],&COORDS[i][1],&COORDS[i][2]);
                                printf(" %f %f %f\n", COORDS[i][0], COORDS[i][1],COORDS[i][2]);
                                i++;
                        }
                        else
                                return;
                k++;
                }//END while

---

do not use feof to control loop - read FAQ

you have 2 fscanf in same iteration to read both END_ELEMENTS and COORDINATES and increment k once

but want to read headers in 2 iterations

This is my suggestion on your program:

Code:

---

/* Array2D.c: Shows how to malloc 2D arrays of type int and double,
by Adak, March 2009.
Status: ok

This is what the data file should have in it:


  ELEMENTS 
          1          2        4        3        1 
          2          5        7        4        2 
          3          4        8        6        3 
          4          7        9        8        4 
END_ELEMENTS 
COORDINATES 
          1  0.000000 10.000000  0 
          2  0.000000 5.000000  1 
          3  5.000000 10.000000  2 
          4  5.000000 5.000000  3 
          5  0.000000 0.000000  4 
          6  10.000000 10.000000 5 
          7  5.000000 0.000000  6 
          8  10.000000 5.000000  7 
          9  10.000000 0.000000  8 
END_COORDINATES
*/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main(void)  {

  FILE * msh_file_ID;
  //Testing the code:
  int i, k, num;
  int nnodes = 9;
  int nelem = 4;
  double garbage = 0.00; //used to force linking to floating point header
       
  char header[32];
  int        **CONN;        //2 *'s for a 2D array
  double **COORDS;
  garbage = sqrt(4);  //force the floating pt packing to load up

  CONN = malloc(nelem * sizeof(int*)); //get memory for 1D
  for (i = 0; i < nelem; i++)  {
      CONN[i] = malloc(4 * sizeof(int));  //get memory for 2D
  }


  COORDS = malloc(nnodes * sizeof(double*));
  for(i = 0; i < nnodes; i++)
    COORDS[i] = malloc(2 * sizeof(double));
       
  msh_file_ID = fopen("Array2D.txt", "rt");
 
  //READ the FIRST LINE OF THE FILE:  ELEMENTS
  fscanf(msh_file_ID, "%s\n", header);
  printf("%s\t\n", header);
 
  i = 0;
  while( !feof(msh_file_ID)){
      for(k = 0; k < nelem; k++) {
        //Read CONN:
        fscanf(msh_file_ID, "%d %d %d %d %d\n",&(CONN[k][0]),&(CONN[k][1]),&(CONN[k][2]),&(CONN[k][3]));
                               
        printf(" %d %d %d %d %d\n ", CONN[k][0], CONN[k][1], CONN[k][2], CONN[k][3]);
      }
      //Read the intermediate strings: "END_ELEMENTS" and "COORDINATES"
      //String END_ELEMENTS
      fscanf(msh_file_ID, "%s\n", header);
      printf("%s\t\n", header);
      //String COORDINATES
      fscanf(msh_file_ID, "%s\n", header);
      printf("%s\t\n", header);
       
      //Read COORDS
      for(i = 0; i < nnodes; i++) {
        fscanf(msh_file_ID, "%d", &num);
        fscanf(msh_file_ID, "%lf %lf", &COORDS[i][0], &COORDS[i][1]);
        printf(" %d. %lf %lf\n", num, COORDS[i][0], COORDS[i][1]);
      }
               
      fscanf(msh_file_ID, "%s", header);
      printf("%s\n", header);

      //if(strcmp(header, "END_COORDINATES") == 0)  //just FYI
                      //break;
  }//END while

  fclose(msh_file_ID);
  printf("\n\n\t\t\t    press enter when ready \n");
  garbage = getchar(); garbage++;

 
  for (i = 0; i < nelem; i++) 
      free(CONN[i]);
  free(CONN);

  for(i = 0; i < 9; i++)
      free(COORDS[i]);
  free(COORDS);

  return 0;
}

---

The if() else() type logic, I didn't like. It made it lean toward being unclear and harder to debug.

I briefly tested the !feof() loop, and found it worked ok in your loop, so I didn't replace it.

Cheers!

Hello Adak,

Thank you so much for replying and helping with your version of the code! It worked perfectly; I really appreciate it.

Thank you again

All the best
cfd