singly linked list with three nodes

[santij93]

/*
Create a singly linked list which contains 3 nodes. The user is requested to provide a single value which will
become the "elem" value for the node.  Then repeat the process 2 more times.  After you have completed the list,
read thru the list from the beginning and print each node.
*/

#include <iostream>
#include <string>
using namespace std;
struct node {
int key;
string name;
node *next;
};
node *firstNode = nullptr;
void addFrontNode (int k, string na) {
node *n = new node;
n->key = k;
n->name = na;
n->next = firstNode;
firstNode = n;
}
void addNewNode (int k, string na, int location) {
node *n = new node;
n->key = k;
n->name = na;
  
node *visitor = firstNode;
node *next = nullptr;
while(visitor != nullptr) {
if(visitor->key == location) {
next = visitor->next;
visitor->next = n;
n->next = next;
break;
}
else
visitor = visitor->next;
}
}
void addLastNode(int k, string na) {
    node *n = new node;
    n->key = k;
    n->name = na;
   
    node *visitor = firstNode;
    node *next = nullptr;
    while(visitor != nullptr) {
next = visitor;
visitor = visitor->next;
}
next->next = n;
   
}
void displayNode() {
node *visitor = firstNode;
while(visitor != nullptr) {
cout << "(" << visitor->key << ", " << visitor->name << ")";
if(visitor->next != nullptr)
cout << "--->";
visitor = visitor->next;
}
cout << endl;
}
int main()
{
addFrontNode(100, "John");
addFrontNode(200, "James");
addFrontNode(150, "Jane");
displayNode();
return 0;
}

The compiler says that on line 22 nullptr was not declared in the scope. I don't know how to fix this

[coder777]

nullptr needs c++11. Either you change the compiler switch or define it yourself like #define nullptr 0

[anarelle]

Probably not my business, but adding node *firstNode = nullptr; as a global variable to be used from within functions is a bad practice. It might not seem like a problem here but if you're learning to code then it's best to use good programming practices from the beginning.