Thread: Segmentation fault

Originally Posted by Miffeltoffel

Guess it should be cell, huh?

Better yet:

Code:

data.field = calloc(data.rows, sizeof(data.field[0]));

Code:

data.field[i] = calloc(data.cols, sizeof(data.field[i][0]));

Welcome to the forum!

I really really hope not to sound rude, but there is a litany of things that are wrong/don't really make sense to me.

1) It makes no sense for setupGeneration to return void** if the only code path returns 0. If setupGeneration() doesn't do anything, why not make it void? Otherwise, the function should return something meaningful other than 0.
2) if you can compile with -g, try gdb ./your_program -> run and then bt when it seg faults. That will print out a stack trace of what was happening, which will tell you exactly where the seg fault is.
3) This line makes no sense:

Code:

data.field = calloc(data.rows,sizeof(char *));

First off, I see you are trying to calloc data.rows elements of something, but data.rows has not been initialized at all as far as I can tell.
Second off, why are the elements you are allocating the size of a pointer to char? It seems like you're trying to assign to field, which is of type cell**. So don't you want sizeof(cell*);
4) Same thing basically:

Code:

data.field[i] = calloc(data.cols, sizeof(char));

Again, data.cols == who knows, while data.field[i] is of type cell*, so it makes no sense to allocate elements the size of a char to it. You'd like the elements to be sizeof(cell).

I don't know exactly what is causing the seg fault. Although trying 2 can help you, you really need to address 1, 3, and 4. I hope that helps at least a little bit.

Oh, thank you guys! I've tried to get main to send the adress, but didn't get it to work, the -> did the trick though!


Now I'm a bit further down the road, but still segfault

Code:

void **setupGeneration (char **argv, game *data){

        printf("i funktion setupGeneration");

        int i,j, line = 0;
        char c;

        FILE *fileOpen;

        fileOpen = fopen(argv[1], "r");

        data->field = calloc(data->rows, sizeof(data->field[0]));
        for(i = 0; i < data->rows; i++){
                data->field[i] = calloc(data->cols, sizeof(data->field[1][0]));

        }



/* segfault? */

        while(c != EOF){

                c = fgetc(fileOpen);

                if(c == '\n'){
                        line++;
                }
                if(line >= 1){

                  /* THIS IS CAUSING SEGFAULT*/
                        data->field[i][j].current = c;

                        printf("%c",c);
                }
        }

        printf("\n");

        return 0;
}

I've identified the reason to the one marked with bold, and I really doubt what I've done there is the correct way of doing it, but I havn't got a clue how else to do it.

Thank you guys for your very informative respnses so far, I'm actually getting somewhere.

Originally Posted by Miffeltoffel

Oh, thank you guys! I've tried to get main to send the adress, but didn't get it to work, the -> did the trick though!


Now I'm a bit further down the road, but still segfault

Code:

void **setupGeneration (char **argv, game *data){

        printf("i funktion setupGeneration");

        int i,j, line = 0;
        char c;

        FILE *fileOpen;

        fileOpen = fopen(argv[1], "r");

        data->field = calloc(data->rows, sizeof(data->field[0]));
        for(i = 0; i < data->rows; i++){
                data->field[i] = calloc(data->cols, sizeof(data->field[1][0]));

        }



/* segfault? */

        while(c != EOF){

                c = fgetc(fileOpen);

                if(c == '\n'){
                        line++;
                }
                if(line >= 1){

                  /* THIS IS CAUSING SEGFAULT*/
                        [I]data->field[j].current = c;

                        printf("%c",c);
                }
        }

        printf("\n");

        return 0;
}

I've identified the reason to the one marked with bold, and I really doubt what I've done there is the correct way of doing it, but I havn't got a clue how else to do it.

Thank you guys for your very informative respnses so far, I'm actually getting somewhere.

Sorry about the pass-by-value stuff, it turns out that what you were doing was fine (and this is fine too). I had a brain fart. My apologizes. Are you absolutely sure that line is the problem? Like did you gdb that?

As a passing glance, would note that j is unintialized, so who knows what's in there? Hence when you go to dereference field you might be out of your address space, which could well be causing your segmentation fault.

Have you considered just reading line by line with fgets()?