Failing to access data from an array - c

Question

I am reading from a file (each line wolds 1 word) and putting each line into an array. However I'll get a segmentation fault whenever I try to access any element in the array. Any help on this is greatly appreciated.
*update: added a while loop to grab the character one by one but I still get a segmentation fault
The pointer was made here:
char* ptr;
I passed it through the function as this:
fillDict(ptr,&size);
int fillDict(char* ptr,int *size)
And it reads the file and puts it into the array here:
int i = -1;
int numb;
int wsize;
while (fgets(word,30,file)!=NULL)
{
if (i==-1)
{
if(word[strlen(word)-1]=='\n')
{
word[strlen(word)-1] = 0;
}
numb = atoi(word);
ptr = malloc(sizeof(char));
}
else
{
if(word[strlen(word)-1]=='\n')
{
word[strlen(word)-1] = 0;
}
wsize = wsize+strlen(word);
ptr = realloc(ptr,wsize);
int j = 0; //added from here
while(j<strlen(word)-1)
{
printf("%d\n",j);
ptr[j] = word[j]; //crashes here
j++;
}
ptr[j] = '\0'; //to here
size++;
}
i++;
}
printf("%s",ptr[0]); //but fails here
fclose(file);

Answer 1

As #Jagannath mentioned, you are treating your ptr variable as a 2 dimensional array.
In reality, you allocate it as a simple buffer.
Schematically :
ptr = [][][][][][][][][][][][][][\0];
Then, you have a word which is also a simple buffer as follow :
word = [h][e][l][l][o][\0];
If you want to copy word to ptr, you need to iterate over both buffers and copy character by character as follow :
word = [h][e][l][l][o][\0];
v v v v v
ptr = [h][e][l][l][o][][][][][][][][][\0];
Otherwise, you can create an array of word by creating a 2 dimensional array.
ptr = [|][|][][]...[\0]
v v
[h][w]
[e][o]
[l][r]
[l][l]
[o][d]
[0][0]
Finally, you have flaws in your code. Look at your malloc(1)... And your wsize is never initialized, so when you do wsize = wsize+strlen(word); the behavior is undefined.

Answer 2

This code shows some fundamental misunderstanding about how pointers work. ptr[i] is equivalent to *(ptr+i). This makes no sense in the context of your code. It is therefore supposed to be a char but you are assigning a pointer to a char to it. And the printf that fails, well of course it's going to fail. it expects a pointer to a char but instead it gets whatever data is at the location ptr is pointing to and treats this as a pointer. This is likely to be a forbidden memory location hence the segfault. Even if it isn't, it is unlikely to reach a null terminating byte before it goes out of bound.