Error in running an implementation of list - c++

Question

This is the part of the code where I'm facing the problem:
#include<iostream>
using namespace std;
struct ID{
int value;
ID *nxtElement;
};
struct SqLand{
ID *id;
SqLand *next;
};
int main(){
for(int p, i = 0; i < 3; i++){
SqLand *nptr = new SqLand;
cin >> p;
ID *buff = new ID;
buff = nptr->id;
for(int j = 0; j < p; j++){
cin >> buff->value;
//cout << "Garbage";
buff = buff->nxtElement;
}
buff = NULL;
//cout << "WILL";
delete nptr;
delete buff;
}
return 0;
}
The problem is that on running this program and inserting the value of p more than 1, the program exits after 2 more inputs.
For example, starting like this:
2
1
3
This is where the program exits
If both the cout statements are un-commented here are the outputs:
2
1
Garbage3
GarbageWILL
And another:
3
1
Garbage2
Garbage
All the programs exit after their respective last lines. What is the error in my program? It's a part of another program so that don't expect this snippet to make any sense. I only want to know where it goes wrong.

Answer 1

What i can understand from your code this ... (with fix)
struct ID {
ID(int val = -1, ID* _nxtElement = NULL) :
value(val), nxtElement(_nxtElement) {
}
int value;
ID *nxtElement;
};
struct SqLand {
SqLand(ID* _id = NULL, SqLand* _next = NULL) :
id(_id), next(_next) {
}
ID *id;
SqLand *next;
};
const int size = 3;
int main() {
SqLand* head = new SqLand;
SqLand* tmp = head;
for (int p, i = 0; i < size; i++) {
cin >> p;
tmp->id = new ID;
ID* tmpID = tmp->id;
for (int j = 0; j < p; j++) {
cin >> tmpID->value;
// avoid unnecessary allocate
if (j < p - 1) {
tmpID->nxtElement = new ID;
tmpID = tmpID->nxtElement;
}
}
// avoid unnecessary allocate
if(i < size - 1) {
tmp->next = new SqLand;
tmp = tmp->next;
}
}
return 0;
}
in your code you miss allocate for nptr->id and you miss the most important the head of list (SqLand *nptr = new SqLand;).