Issue inserting node in linked list - c

Question

I am practicing creating a link list, but encountered a problem when trying to insert an item to the front of the list. The code in my insert function works properly if I put it within main, but not when run separately as a function.
I am using a pointer as a argument in the function so I don't understand why the value in my print statement isn't changing to 100 which should be at the front of the linked list using the insert function (When I run the function 61 is printed, I am aiming for 100 to be printed).
Thanks for the help!
#include <stdio.h>
#include <stdlib.h>
typedef struct node *nodePtr;
typedef struct node node;
struct node {
int value;
nodePtr next;
};
node insert(node *first, int value)
{
nodePtr temp;
temp = malloc(sizeof(node));
temp->value = value;
temp->next = first;
first = temp;
}
int main()
{
nodePtr first;
first = malloc(sizeof(node));
first->value = 61;
first->next = NULL;
insert(first, 100);
printf("%d", first->value);
}

Answer 1

your passing a pointer to the node as a argument to the function and changing the value of formal parameter does not change the value of the actual parameter do this it should work.
enter code here
#include <stdio.h>
#include <stdlib.h>
typedef struct node *nodePtr;
typedef struct node node;
struct node {
int value;
nodePtr next;
};
void insert(node **first, int value)
{
nodePtr temp;
temp = malloc(sizeof(node));
temp->value = value;
temp->next = *first;
*first = temp;
}
int main()
{
nodePtr first;
first = malloc(sizeof(node));
first->value = 61;
first->next = NULL;
insert(&first, 100);
printf("%d",first->value);
}

Answer 2

You have passed a pointer to function insert() and stored it in a variable first whose scope is local to function insert(). Now you have
updated pointer first in function insert().
When you will return to main() function updated value of pointer next is lost that is why you are getting unexpected result while printing value in main().
To summarise:
first = malloc(sizeof(node)); // let's say first is p1
...
insert(first, 100); // first is P1
....
node insert(node *first, int value) // first is p1
....
tmp = malloc(sizeof(node)); // let's say tmp is p2
first = temp; // Now first has become p2 but its scope is local to insert()
....
printf("%d", first->value); // first is still p1 here
Solution
node* insert(node *first, int value)
{
nodePtr temp;
temp = malloc(sizeof(node));
temp->value = value;
temp->next = first;
first = temp;
return first;
}
int main()
{
nodePtr first;
first = malloc(sizeof(node));
first->value = 61;
first->next = NULL;
first = insert(first, 100);
printf("%d", first->value);
return 0;
}