cin a pointer reference to a struct - c++

Question

I am using cin and cout in my program. I starts off fine because it is not executing any of the functions, but after you type your name, it throws an exception in the iostream library. wondering if it is a problem with using cin through refrence.`
// linkedlists.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <iostream>
#include <string>
using namespace std;
struct person {
string name;
int age;
struct person* next;
};
person *head = NULL;
int length() {
int count = 0;
person *current = head;
while (current->next != NULL) {
current = current->next;
count++;
}
return count;
}
void printlist() {
person *current = head;
while (current->next != NULL){
cout << "Name: " << current->name << " Age: " << current->age << "\n";
current = current->next;
}
}
void insert() {
// int choice;
person *newNode = (struct person*)malloc(sizeof(person));
//cout << "Press 1 to insert at beginning of list.\n";
//cin >> choice;
// switch (choice) {
//case 1:
newNode->next = head;
head = newNode;
cout << "What is this person's name?\n";
cin >> newNode->name;
cout << "\nWhat is the age of " << newNode->name << "?";
cin >> newNode->age;
cout << "The current list of people is " << length() << " long.\n";
printlist();
}
void menu() {
int choice;
cout << "Welcome to the person recorder! ";
bool inloop = true;
while (inloop) {
cout << "Press 1 to add more entries. Press 2 to print the entire list. Press 3 to exit the program.\n";
cin >> choice;
switch (choice) {
case 1:
insert();
case 2:
printlist();
case 3:
inloop = false;
}
}
}
/*void change(person* human) {
string temp_name;
int temp_age;
cout << "What is this person's name?\n";
cin >> temp_name;
cout << "\nWhat is this person's age?\n";
cin >> temp_age;
human->name = temp_name;
human->age = temp_age;
}
*/
int main()
{
menu();
}
using visual studio 2015, am a noob to c/c++ and trying to make a linked list.

Answer 1

The problem is caused by your allocation of person:
person *newNode = (struct person*)malloc(sizeof(person));
This will allocate memory on the heap for an instance of person, but it will not call the constructor of person and any of it's members. This does not matter for age and next since they are primitive types, but name is an std::string, which has a constructor that needs to be called for it to function properly.
In C++ you create instances of objects using the keyword new.
person *newNode = new person;
This will create a new instance of person, and also call its constructor, which will initialize name properly.
Once you are done with the instance of person, you will have use the keyword delete to clean it up.
delete newNode;
Similar to the difference between malloc and new, delete will free the memory, but also call the destructor, which is used by name to clean up any resources it may have allocated to store the string.