not woking c program for SLL [closed] - c

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Q please help me this program is not working properly.
not displaying the value.this program is an example of singly linked list which I am trying to run on c.
`
#include<stdio.h>
#include<stdlib.h> //malloc defined
struct node
{
int data;
struct node *next;
};
add() //add function
{
int value;
struct node *n;
n=(struct node*)malloc(sizeof(struct node)); //mem allocation
printf("enter the value to add\n");
scanf("%d",&value);
n->data=value;
n->next=NULL;
// n=n->next;
// n->next=NULL;
}
delete() //delete function
{
// n=n->next;
struct node *n; //declaration
printf("the node deleted is %d",n->data);
free(n);
}
display() //display function
{
struct node *n;
while(n!=NULL)
{
printf("%d",n->data);
n=n->next;
}
}
int main()
{
int ch;
while(1)
{
printf("do you want to add node press 1\n");
printf("do you want to delete node press 2\n");
printf("do you want to display node press 3\n");
printf("do you want to exit press 4\n");
scanf("%d",&ch);
switch(ch)
{
case 1:add();
break;
case 2:delete();
break;
case 3:display();
break;
case 4:exit(0);
default: printf("wrong choice!!!\n");
}
}
return 0;
getch();
}
please help me this program is not working properly.
not displaying the value.this program is an example of singly linked list which I am trying to run on c.

Answer 1

printf("%d",n->data); is not printed because:
struct node *n; // n is not determined.
while(n != NULL) // undefined behaviour
n is different from the other n that is in the add() function. You never passed the struct to the other functions so it will not do what you wanted it to do.

Answer 2

in the function display(), the local variable 'n' is only declared but not defined, so here 'n' is only a wild pointer. It's happened in the function delete() as well.
it's not a correct way to implement the single linked list. In the function add() what you wrote is only create a node, but not add a node to linked list.

Answer 3

#include<stdio.h>
#include<stdlib.h> //malloc defined
struct node
{
int data;
struct node *next;
}*n,*p;
create() //add function
{
int value;
n=(struct node*)malloc(sizeof(struct node)); //mem allocation
printf("enter the value to add\n");
scanf("%d",&value);
n->data=value;
n->next=NULL;
}
add()
{
int value;
// struct node *p;
p=(struct node*)malloc(sizeof(struct node));
printf("enter the value to add next\n");
scanf("%d",&value);
n->next=p;
p->data=value;
p->next=NULL;
}
delete() //delete function
{
printf("the node deleted is %d",p->data);
n->next=NULL;
free(p);
}
display() //display function
{
while(n!=NULL)
{
printf("%d\n",n->data);
n=n->next;
}
}
int main()
{
int ch;
while(1)
{
printf("do you want to create node press 1\n");
printf("do you want to add node press 2\n");
printf("do you want to delete node press 3\n");
printf("do you want to display node press 4\n");
printf("do you want to exit press 5\n");
scanf("%d",&ch);
switch(ch)
{
case 1:create();
break;
case 2:add();
break;
case 3:delete();
break;
case 4:display();
break;
case 5:exit(0);
default: printf("wrong choice!!!\n");
}
}
return 0;
getch();
}