Simple Stack implementation

#include <iostream>

#include<stdio.h>

struct  stack

{

    int data;

    struct stack* next;

};

struct stack* tos=nullptr;

struct stack* getNewNode(const int d)

{

    struct stack* newNode= (struct stack* )malloc(sizeof(struct stack));

    if(!newNode)

    {

        std::cout<<"Unable to allocate memory\n";

        exit(0);

    }

newNode->data=d;

newNode->next=nullptr;

return newNode;

}

void push(struct stack** aTos, int data)

{

struct stack*node=getNewNode(data);

node->next=(*aTos);

(*aTos)=node;

}

bool stackEmpty()

{

    return (tos)?true:false;

}

struct stack* pop()

{

    if(!stackEmpty())

    {

        std::cout<<"Stack is empty\n";

        exit(0);

    }

    struct stack* temp=tos;

    tos=tos->next;

    return temp;

}

int main()

{

    push(&tos,1);

    push(&tos,2);

    push(&tos,3);

    push(&tos,14);

    push(&tos,5);

    push(&tos,8);

    std::cout<<"POPED value = "<<pop()->data<<"\n";

    std::cout<<"POPED value = "<<pop()->data<<"\n";

    std::cout<<"POPED value = "<<pop()->data<<"\n";

    std::cout<<"POPED value = "<<pop()->data<<"\n";

    std::cout<<"POPED value = "<<pop()->data<<"\n";

    std::cout<<"POPED value = "<<pop()->data<<"\n";

    std::cout<<"POPED value = "<<pop()->data<<"\n";

}