My variables changing after moving to the next function - c

Question

I have a problem in my homework that i cannot seem to solve, The task it to create some sort of tool for a city to handle families information, after I add a family successfuly in the function "add_new_family" and move to "add_new_child" while working with the debugger i've noticed that just by moving up to first or second line of the function my original structure variables are changing randomly, the paretns name changes to garbage and if i move on with the function and actually try to add another child, it saves the information on the parents name and such, i cant seem to figure out the cause of this problem.
Please excuse my memory allocation casting if it bothers anyone, I've read before in stackoverflow that it might not be necessary but my professor insist.
There might be other crucial problems with my code, im a first year student, although it would be appreciated if you note it, but my main focus is just figuring out the cause of those random changes after I send my struct to the "add_new_child" function, I add an image of before and after to make clear of whats happening picture
#define _CRT_SECURE_NO_WARNINGS
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <stdio.h>
#define SIZE 10000;
typedef struct person {
char* name;
int gender;//1-female, 0-male
}Person;
typedef struct {
char* family_name;
Person* mother, *father; // parents' names
Person* *children_list;// list of the children in this family
unsigned child_list_size; // size of child_list array
unsigned current_listChild_size;
}Family;
typedef struct {
Family** list;
unsigned current_listFamily_size; // current size of family
}ListFamilys;
ListFamilys* new_city(ListFamilys* s);
void add_new_family(ListFamilys* s, char* fname);
void add_new_child(ListFamilys* s, char* surname);
void main()
{
ListFamilys* list = (ListFamilys*)malloc(1 * sizeof(ListFamilys));
assert(list);
list = new_city(list);
add_new_family(list, "james");
add_new_child(list, "james");
system("pause");
}
ListFamilys* new_city(ListFamilys* s)
{
assert(s->list = (Family**)calloc(1, sizeof(Family*)));
s->current_listFamily_size = 0;
return s;
}
void add_new_family(ListFamilys* s, char* fname)
{
unsigned int size = SIZE;
if (s->current_listFamily_size >= size)
{
printf("\nAccording to our database, it will not be possible to add another family in Angola, as the city reached its capacity");
return;
}
for (unsigned int i = 0; i < s->current_listFamily_size; i++)
{
if (strcmp(s->list[i]->family_name, fname) == 0)
{
printf("\nERROR 1: A family with the surname of %s already exist in the database", fname);
return;
}
}
s->current_listFamily_size += 1;
/*assert(s = (ListFamilys*)realloc(s, s->current_listFamily_size * sizeof(ListFamilys)));
assert(s->list = (Family**)calloc(1 , sizeof(Family*)));*/
assert(s->list[s->current_listFamily_size - 1] = (Family*)calloc(1, sizeof(Family)));
assert(s->list[s->current_listFamily_size - 1]->father = (Person*)malloc(1 * sizeof(Person)));
assert(s->list[s->current_listFamily_size - 1]->mother = (Person*)calloc(1, sizeof(Person)));
int numOfParents = 0;
printf("Creating new data for the [%s] family, please provide the number of parents (1/2): ", fname);
scanf("%d", &numOfParents);
s->list[s->current_listFamily_size - 1]->family_name = fname;
char tmpname[100];
char tmpname1[100];
int tmpgender = 0;
int tmpgender1 = 0;
switch (numOfParents)
{
case 0:
printf("\nERROR 2: A newly created family cannot contain no parents at all or more than 2 parents, please try again.");
return;
case 1:
printf("\nPlease provide the name of the parent No.1: ");
scanf("%s", tmpname);
printf("\nPlease provide the gender of parent No.1 [1 for female / 0 for male]: ");
scanf("%d", &tmpgender);
if (tmpgender == 0)
{
s->list[s->current_listFamily_size - 1]->father->gender = tmpgender;
s->list[s->current_listFamily_size - 1]->father->name = tmpname;
s->list[s->current_listFamily_size - 1]->mother = NULL;
}
else
{
s->list[s->current_listFamily_size - 1]->mother->gender = tmpgender;
s->list[s->current_listFamily_size - 1]->mother->name = tmpname;
s->list[s->current_listFamily_size - 1]->father = NULL;
}
break;
case 2:
printf("\nPlease provide the name of the parent No.1:");
scanf(" %s", tmpname);
printf("\nPlease provide the gender of parent No.1 [1 for female / 0 for male]: ");
scanf("%d", &tmpgender);
printf("\nPlease provide the name of the parent No.2:");
scanf(" %s", tmpname1);
printf("\nPlease provide the gender of parent No.2 [1 for female / 0 for male]: ");
scanf("%d", &tmpgender1);
if (tmpgender == 0)
{
s->list[s->current_listFamily_size - 1]->father->gender = tmpgender;
s->list[s->current_listFamily_size - 1]->father->name = tmpname;
s->list[s->current_listFamily_size - 1]->mother->gender = tmpgender1;
s->list[s->current_listFamily_size - 1]->mother->name = tmpname1;
}
else
{
s->list[s->current_listFamily_size - 1]->mother->gender = tmpgender;
s->list[s->current_listFamily_size - 1]->mother->name = tmpname;
s->list[s->current_listFamily_size - 1]->father->gender = tmpgender1;
s->list[s->current_listFamily_size - 1]->father->name = tmpname1;
}
break;
default:
printf("\nERROR 2: A newly created family cannot contain no parents at all or more than 2 parents, please try again.");
return;
}
int numOfChildren = 0;
printf("\nPlease provide the number of children in the [%s] family: ", fname);
scanf("%d", &numOfChildren);
if (numOfChildren == 0)
{
s->list[s->current_listFamily_size - 1]->children_list = NULL;
s->list[s->current_listFamily_size - 1]->child_list_size = 0;
s->list[s->current_listFamily_size - 1]->current_listChild_size = 0;
}
else
{
assert(s->list[s->current_listFamily_size - 1]->children_list = (Person**)malloc((numOfChildren + 2) * sizeof(Person*)));
s->list[s->current_listFamily_size - 1]->child_list_size = numOfChildren + 2;
for (int i = 0; i < numOfChildren; i++)
{
char tmpname2[100];
tmpgender = 0;
printf("\nPlease provide the name of the child No.%d:", i+1);
scanf(" %s", tmpname2);
printf("\nPlease provide the gender of child No.%d [1 for female / 0 for male]: ", i+1);
scanf("%d", &tmpgender);
assert(s->list[s->current_listFamily_size - 1]->children_list[i] = (Person*)malloc(1 * sizeof(Person)));
s->list[s->current_listFamily_size - 1]->children_list[i]->gender = tmpgender;
s->list[s->current_listFamily_size - 1]->children_list[i]->name = tmpname2;
}
for (int i = 0; i < 2; i++)
{
s->list[s->current_listFamily_size - 1]->children_list[numOfChildren + i] = NULL;
}
s->list[s->current_listFamily_size - 1]->current_listChild_size = numOfChildren;
}
printf("\nFamily was added to the database SUCCESSFULY.");
return;
}
void add_new_child(ListFamilys* s, char* surname)
{
int truth = 0;
unsigned int index = 0;
for (unsigned int i = 0; i < s->current_listFamily_size; i++)
{
if (strcmp(s->list[i]->family_name , surname) == 0)
{
index = i;
truth = 1;
}
}
if (truth == 0)
{
printf("\nERROR 3: Family wasnt found in the database, try again");
return;
}
char tmpname4[100];
int gender = 0;
if (s->list[index]->current_listChild_size < s->list[index]->child_list_size)
{
printf("\nPlease provide the name of the child: ");
scanf(" %s", tmpname4);
printf("\nPlease provide the gender of child [1 for female / 0 for male]: ");
scanf("%d", &gender);
assert(s->list[index]->children_list[s->list[index]->current_listChild_size] = (Person*)malloc(1 * sizeof(Person)));
s->list[index]->children_list[s->list[index]->current_listChild_size]->gender = gender;
s->list[index]->children_list[s->list[index]->current_listChild_size]->name = tmpname4;
}
else
{
s->list[index]->child_list_size += 1;
s->list[index]->current_listChild_size += 1;
assert(s->list[index]->children_list = (Person**)malloc(1 * sizeof(Person*)));
printf("\nPlease provide the name of the child: ");
scanf(" %s", tmpname4);
printf("\nPlease provide the gender of child [1 for female / 0 for male]: ");
scanf("%d", &gender);
s->list[index]->children_list[s->list[index]->current_listChild_size] = (Person*)malloc(1 * sizeof(Person));
s->list[index]->children_list[s->list[index]->current_listChild_size]->gender = gender;
s->list[index]->children_list[s->list[index]->current_listChild_size]->name = tmpname4;
}
printf("\nChildren information was updated SUCCESSFULY");
return;
}

Answer 1

You're setting the name member to a pointer to a local variable, which becomes invalid when the function returns. You need to make a dynamic copy of the string.
s->list[s->current_listFamily_size - 1]->father->name = strdup(tmpname);
The same thing for the family name, mother's name and all the children names.

Answer 2

As already pointed out in another answer, your string handling is full of bugs as you save pointers to variables instead actually creating a string copy (i.e. strcpy).
Another issue is s->list. It seems you want it to be a pointer to an array of pointers because you access it like: s->list[s->current_listFamily_size - 1]->...
But you never allocate more than one pointer. Here:
s->list = (Family**)calloc(1, sizeof(Family*))
In other words - the only valid index is zero.
s->list[0]->... // Is OK
s->list[1]->... // Is very bad
You need to add more pointers when you add a Family