C (BEGINNER ) - Writing a 2D array into a file

Question

Hello i would like to store a matrix into a file here's the code I made

void fichier_print(grid_t grille, int n){
  int i,j;
  FILE *f_solution;
  f_solution=fopen("solution.txt","wb");
  if( f_solution == NULL )
  {
     printf("Le fichier est corronpu");
     exit(1);
  }
  for (i=0; i<n; i++){
    for (j=0; j<n; j++){
      fprintf(f_solution,"%c\n",grille.data[i][j]);
    }
    printf("|\n");
  }
  printf("\n");

  fclose(f_solution);

}

Here grille.data is the matrix that i want to save in a file .

The thing is that when i run the code nothing appears no .txt ( I made sure that I was in the correct directory before saying this ) .

Is there anyone with a clue ? Thanks

You did not check to see if the file opened successfully. If it fails you should dump the OS error. — Martin James, Jan 15 '22 at 16:15
Hello I re-edited my code ( I am a beginner ) , so i add if( f_solution == NULL ) , but still nothing happens — Marouane Sharry, Jan 15 '22 at 16:21
@MarouaneSharry well yes it's pretty clear that it is some structure, but __what__ is that structure? Depending on how the structure is defined, the code you show may make sense or not. [Edit] your question. — Jabberwocky, Jan 15 '22 at 16:23
If your code does not display `Le fichier est corrompu` this either means: 1. you never call `fichier_print`, or 2. the file "solution.txt" is in another directory than the one you think. It depends on your environnment, your OS, your IDE and posibly a few other things. — Jabberwocky, Jan 15 '22 at 16:27
@Jabberwocky so in grid_t i have **data** which is a unsigned char ** I used to create a matrix and int **size** giving the size of the matrix . — Marouane Sharry, Jan 15 '22 at 16:29
@MarouaneSharry don't describe your code, but show it in the question. Make sure you _actually_ call `fichier_print`, by putting something like `printf("fichier_print called\n");` at the beginning of `fichier_print `, or by using your debugger. — Jabberwocky, Jan 15 '22 at 16:31
@Jabberwocky I am so dumb i forgot to call the function still learning thanks ! — Marouane Sharry, Jan 15 '22 at 16:35
I’m voting to close this question because the OP found out himself that he didn't even call the function, sigh. — Jabberwocky, Jan 15 '22 at 16:43

score 0 · Accepted Answer · answered Jan 15 '22 at 16:41

I did a simplified guess on your structure (not looking at your comments). Assuming that your data structure is correctly initilized, then it should print correctly.

But since on your end there is a problems getting the file you want, my guess is that grille content (or in combination with n) the data is not properly initialized.

E.g. (the simplified version)

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

struct grid {
    char data[10][10];
};
typedef struct grid grid_t;

void fichier_print(grid_t grille, int n) {
    FILE *f_solution = fopen("solution.txt", "wb");
    if (f_solution == NULL) {
        perror("fopen");
        printf("Le fichier est corronpu");
        exit(EXIT_FAILURE);
    }
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) fprintf(f_solution, "%c\n", grille.data[i][j]);
        printf("|\n");
    }
    printf("\n");
    fclose(f_solution);
}

int main(void) {
    grid_t g;
    memset(&g, 'x', sizeof g);
    fichier_print(g, 10);
    return EXIT_SUCCESS;
}

The perror would also help in clarifying what (might) be wrong when opening/creating a file.

OP didn't even call the function, so your answer is somewhat pointless... — Jabberwocky, Jan 15 '22 at 16:45

C (BEGINNER ) - Writing a 2D array into a file

1 Answers1