top is not global variable so why peek is able to use it even without passing that .plz reply

Question

#include<stdio.h>
#include<stdlib.h>

struct Node{
int data;
struct Node * next;
};

struct Node* top = NULL;

void linkedListTraversal(struct Node *ptr)
{
while (ptr != NULL)
{
printf("Element: %d\n", ptr->data);
ptr = ptr->next;
}
}

int isEmpty(struct Node* top){
if (top==NULL){
return 1;
}
else{
return 0;
}
}

int isFull(struct Node* top){
struct Node* p = (struct Node*)malloc(sizeof(struct Node));
if(p==NULL){
return 1;
}
else{
return 0;
}
}

struct Node* push(struct Node* top, int x){
if(isFull(top)){
printf("Stack Overflow\n");
}
else{
struct Node* n = (struct Node*) malloc(sizeof(struct Node));
n->data = x;
n->next = top;
top = n;
return top;
}
}

int pop(struct Node* tp){
if(isEmpty(tp)){
printf("Stack Underflow\n");
}
else{
struct Node* n = tp;
top = (tp)->next;
int x = n->data;
free(n);
return x;
}
}

int peek(int pos){
struct Node* ptr = top;
for (int i = 0; (i < pos-1 && ptr!=NULL); i++)
{
ptr = ptr->next;
}
if(ptr!=NULL){
return ptr->data;
}
else{
return -1;
}

}

int main(){
top = push(top, 28);
top = push(top, 18);
top = push(top, 15);
top = push(top, 7);

linkedListTraversal(top);
for (int i = 1; i <= 4; i++)
{
printf("Value at position %d is : %d\n", i, peek(i));
}

return 0;
}

Answer 1

Isn't "top" global variable, as you declare it outside of all functions?