Question

Working on some code for a machine problem; we’ve just started working with pointers, etc, and so I’m not quite sure where it’s wrong. Running debugging is showing that it’s the line: for(i=0; i<*y;i++) that is throwing the error, though I’m sure whatever’s wrong is also wrong in the for(j=0;j<*x;j++) space. Any help would be greatly appreciated.

    int readImage(char* fileName,
                  int image[MAX_IMAGE_SIZE][MAX_IMAGE_SIZE][NUM_CHANNELS],
                  int* x,
                  int* y,
                  int* max)
    {
        /* Variable declarations*/
        int i=0; 
        int j=0;
        int k=0;
        int num=0;
        char c;
        /* Opens file, skips first line*/
        FILE *input=fopen(fileName, "r");
        if(!input)
            return -1;
        do
            c=getc(input);
        while(c!='\n');
        /*Saves the x and y components into a variable */
        fscanf(input,"%d",&x);
        fscanf(input,"%d",&y);
        fscanf(input,"%d",&max);
        /*Cycles through file, reading it into the array */
        for(i=0; i<*y;i++)
        {
            for(j=0;j<*x;j++)
            {
                for(k=0;k<NUM_CHANNELS; k++)
                {
                    /*Takes input */
                    fscanf(input, "%d",&num);
                    /*Stores into the array in the form of array[x][y][color] */
                    image[j][i][k]=num;
                }
            }
        }
        /*Closes input  */
        fclose(input);
        return 0;
    }

Answer 1

Variables x, y and max are already pointers. So you don’t need to use address-of & in the fscanf(). Also, you need to allocate memory for them if the caller didn’t.

Just use:

  fscanf(input,"%d",x);
  fscanf(input,"%d",y);
  fscanf(input,"%d",max);

And make sure memory is allocated for them by the caller. Otherwise, use malloc()