Dynamic array with dynamic string.Error reading characters of string - c

Question

I need to create dynamic array of Parents where lastname is dynamic.
But I receive an error about error reading characters of string.
parent ** getParents(){
parent parent_in;
parent** parentsArray=NULL;
char answer;
int i, numOfParents=0,fExit=0;
do
{
printf("Do you wan't to enter parent? Y/N\n");
flushall();
scanf("%c", &answer);
if (answer == 'N')
{
fExit = 1;
}
else
{
parent_in.lastname = (char*)malloc(20 * sizeof(char));
parentsArray = (parent**)realloc(parentsArray, 1 * sizeof(parent*));
parentsArray[numOfParents] = (parent*)calloc(1, sizeof(parent));
printf("Please enter the lastname and num of childrens\n");
scanf("%s %d", &parentsArray[numOfParents]->lastname, &parentsArray[numOfParents]->numOfChildren);
numOfParents++;
free(parent_in.lastname);
}
} while (fExit == 0);
return parentsArray;
}
Here is struct of parents:
struct Parents{
char *lastname;
int numOfChildren;
}typedef parent;

Answer 1

Your code is a bit wired, as you mix the use of data structure parent_in with the use of parentsArray and it's entries; you malloc on the one, and use it at the other (e.g. concerning parent_in).
But concerning your error, there are two main issues that I see immediately:
You scanf a string into a non-initialized pointer, i.e scanf("%s %d", &parentsArray[numOfParents]->lastname, .... Note that you might have reserved space for a parents structure; this structure has a pointer to lastname, which for itself does not get "malloced".
You (re)-allocate always to the same number of entries, i.e. 1 in
parentsArray = (parent**)realloc(parentsArray, 1 *
sizeof(parent*)). You probably meant realloc(parentsArray,
(numOfParents+1) * sizeof(parent*)).
I suppose that point 1 is responsible for your "error reading characters of string"; If you overcome this, I'm rather sure that point 2 will lead to the next memory corruption.