segmentation fault while trying to read in from file to a 2D array

Question

I am getting a segmentation fault while trying to read from a file into a 2D dynamic array. I know this is a little vague of a question, but this being my first C code, I haven't been able to trace out what the problem is. Any direction will be appreciated. These are my variables:

int i;
    int rowsize=0;
    int colsize=0;
    int colenter=0;
    int rowenter=0;
    int colexit=0;
    int rowexit=0;

    char  sizestring[20];
    char  enterstring[20];
    char  exitstring[20];
    int   line=0;
    int j;
    int k;
    char**mazearray;
    FILE*file;

And this is my allocation.

mazearray = (char**) malloc(sizeof(char*)*rowsize);

    for(i =0; i<rowsize; ++i)
    {
            mazearray[i]= (char*)malloc(sizeof(char)*colsize);
    }

And this is me trying to read from a file and parse the information. I first try to read in 3 lines of strings which contain the information about a maze (Array size, enterance, exit etc.) and then try to fill out the 2d array with the for loop at the bottom.

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

    if (!file)
    {
            printf("The file is not connected/n");
    }
    while (!feof(file))
    {

            while(line<3)
            {
                    if(line==0)
                    {

                            fgets(sizestring,20,file);
                            sscanf(sizestring,"%d,%d", &colsize, &rowsize);
                            line++;
                    }
                    else if(line ==1)
                    {
                            fgets(enterstring,20,file);
                            sscanf(enterstring,"%d,%d",&colenter, &rowenter);
                            line++;
                    }
                    else if(line ==2)
                    {
                            fgets(exitstring,20,file);
                            sscanf(exitstring, "%d,%d", &colexit, &rowexit);
                            line++;
                    }
            }
            for(j=0; j<rowsize; j++)
            {
                    for(k=0; k<colsize; k++)
                    {
                            fscanf(file,"%c",&mazearray[j][k]);
                    }
            }
    }
    fclose(file);

Again any direction will help. Thanks

So when are you doing the allocations? Before reading the actual size? — Sami Kuhmonen, Oct 09 '17 at 10:11
i think the problem may be here `int rowsize=0; int colsize=0;` — roottraveller, Oct 09 '17 at 10:11

score 1 · Accepted Answer · answered Oct 09 '17 at 10:54

1

rowSize and colSize are both zero:

mazearray = (char**) malloc(sizeof(char*)*rowsize);

for(i =0; i<rowsize; ++i)
{
        mazearray[i]= (char*)malloc(sizeof(char)*colsize);
}

No bytes will be allocated to mazearray. The for loop will be executed no times.

I see you read in rowSize and colSize from stdin but having read them, you do not allocate your arrays at any point with the new sizes.

answered Oct 09 '17 at 10:54

JeremyP

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Thank you. I am not having seg fault anymore. But I still can't read in with the for loop at the bottom. I can read the first three lines. – Christine Harper Oct 09 '17 at 11:03

segmentation fault while trying to read in from file to a 2D array

1 Answers1