Inputting Values in the members of structure through linked list - c

Question

I am working in C. Here, I have a structure Node with data members passengers and station. I have a function which inputs the passenger number and stop Name from the user.
struct Node
{
int stopNo;
int passenger;
char station[50];
struct node* next;
};
I have a function which takes the input as the name of station and passengers no and automatically increase the stopNo by 1.
I am trying to Use a linked list to store the stations.
#include<stdio.h>
#include<stdlib.h>
struct Node
{
int stopNo;
int passenger;
char station[50];
struct node* next;
};
void takeInput(struct Node* head)
{
head->stopNo = head->stopNo +1;
printf("Station Name");
scanf(" %[^\n]s",head->station);
printf("New Passengers ");
scanf("%d",&head->passenger);
}
void printStops(struct Node* head)
{
for(int i=0;i<=head->stopNo;i++)
{
printf("Stop %d. %s with %d passenger",head->stopNo,head->station,head->passenger);
}
}
int main()
{ int n;
struct Node* head = NULL;
struct Node* second = NULL;
//Memory Allocation into heap
head = (struct Node*)malloc(sizeof(struct Node));
second = (struct Node*)malloc(sizeof(struct Node));
while(1){
//Menu
printf("1.Log Stops\n");
printf("2.Print Stop");
printf("3.Exit");
scanf("%d",&n);
switch(n){
case 1:
takeInput(struct Node*);
break;
case 2:
printStops(struct Node*);
break;
case 3:
exit(0);
default:
printf("Enter the numbers from 1 to 2");
}
}
}
I am confused what to pass as an argument through the function.

Answer 1

You are mis-using the linked list concept.
The principle is to dynamically add new nodes at the beginning (simpler) or at the end (slightly more complex). Here, as you already have a function dedicated to feeding the list, you could just allocate the nodes there. A possible way is to pass the address of the current head, and let the function change it. But you have to define a sentinel value to tell the function that you do not want to input more nodes.
In the following code "STOP" is that sentinel:
void takeInput(struct Node **head)
{
int stopNo = 0;
for (;;) {
struct Node *node = malloc(sizeof (*node));
node->stopNo = stopNo++;
node->next = *head;
printf("Station Name");
scanf(" %[^\n]",node->station);
if (strcmp(node->station, "STOP") == 0) { // no more station
free(node);
break;
}
printf("New Passengers ");
scanf("%d",&node->passenger);
*head = node;
}
}
That way, you can iterate the list to print its content:
void printStops(struct Node* head)
{
while (head != NULL)
{
printf("Stop %d. %s with %d passenger\n",head->stopNo,head->station,head->passenger);
head = head->next;
}
}
Finally, you main would become:
int main()
{ int n;
struct Node* head = NULL;
while(1){
//Menu
printf("1.Log Stops\n");
printf("2.Print Stop\n");
printf("3.Exit\n");
scanf("%d",&n);
switch(n){
case 1:
takeInput(&head);
break;
...