figure out pointers and structs - c++

Question

I've been trying to figure out how to deal with pointers & structs. I wrote the following code.
#include <iostream>
using namespace std;
struct Person
{
char name[20]; //Question 2
int id;
};
const int max_num_of_childs=10;
struct Family
{
Person dad;
Person mom;
int num_of_childs;
Person* child[max_num_of_childs];
};
void add_child (Family& f)
{
char answer;
do
{
if (f.num_of_childs==max_num_of_childs)
{
cout << "no more children" <<endl;
return;
}
cout << "more child? Y/N" <<endl;
cin >> answer;
if (answer == 'Y')
{
f.child[f.num_of_childs] = new Person;
cout << "enter name and id" << endl;
cin >> f.child[f.num_of_childs]->name;
cin >> f.child[f.num_of_childs]->id;
f.num_of_childs++;
}
}
while (answer=='Y');
return;
}
void add (Family& f)
{
cout << "insert dad name & id" << endl;
cin >> f.dad.name >> f.dad.id;
cout << "\ninsert mom name & id" << endl;
cin >> f.mom.name >> f.mom.id;
add_child (f);
}
void print_child (const Family f) //Question 1
{
for (int i=0; i<f.num_of_childs; i++)
cout << "#" << i+1 << "child name: " << f.child[f.num_of_childs]->name << "child id: " << f.child[f.num_of_childs]->id << endl;
}
void print (const Family f)
{
cout << "dad name: " << f.dad.name << "\tdad id: " << f.dad.id << endl;
cout << "mom name: " << f.mom.name << "\tmom id: " << f.mom.id << endl;
print_child (f);
}
int main()
{
Family f;
f.num_of_childs=0;
add(f);
print(f);
return 0;
}
Why is the output of print_child() gibberish?
dad name: AAAA dad id: 11
mom name: BBBB mom id: 22
1child name: ï Uï∞ u u u h░├evhchild id: 6846053
2child name: ï Uï∞ u u u h░├evhchild id: 6846053
How can I define an array of chars with unlimited length? (using string also requires a defined length).

Answer 1

Why is the output of print_child() gibberish?
In the print_child() method, code is reaching out of initialized range of f.child array. There is:
void print_child (const Family f) //Question 1
{
for (int i=0; i<f.num_of_childs; i++)
cout << "#" << i+1 << "child name: " << f.child[f.num_of_childs]->name << "child id: " << f.child[f.num_of_childs]->id << endl;
}
I believe there should be:
void print_child (const Family f) //Question 1
{
for (int i=0; i<f.num_of_childs; i++)
cout << "#" << i+1 << "child name: " << f.child[i]->name << "child id: " << f.child[i]->id << endl;
}
i is always smaller then f.num_of_childs, so code will not reach uninitialized memory.
Apart of this there is one more small thing.
Usually integer class members get initialized to 0, but this is not guarantied. I would recommend initialization, to ensure that initial value of num_of_childs is 0 when object of Family class is created:
struct Family
{
Person dad;
Person mom;
int num_of_childs = 0;
Person* child[max_num_of_childs];
};