whenever i delete a node and call display loop runs infinitely

[Naveen Bansal]

//program to implement lists through liked list

incert

#include<stdio.h>
#include<malloc.h>
struct node{
int data;
struct node *next;
 };
void incert(int num,node *pointer)
   {
   while(pointer->next!=NULL)
   pointer=pointer->next;
   pointer->next=(node *)malloc(sizeof(node));
   pointer=pointer->next;
   pointer->data=num;
   pointer->next=NULL;
   }
void display(node *pointer)
{
     while(pointer->next!=NULL)
    {
        printf("%d->",(pointer->next)->data);
        pointer=pointer->next;
     }
     printf("\n");
}
void del(int num,node *pointer)
{
    while(((pointer->next)->data!=num)&&(pointer->next!=NULL))
    {
        
        pointer=pointer->next;
     }
     
     
        if(pointer->next==NULL)
        
                 printf("element not found");
                 
        else
            {
                 node *t;
                 t=(node *)malloc(sizeof(node));
                 t=pointer->next;
                 pointer=t->next;
                 free(t);
             }
    
    return;
}


main()
{    int num,choice;
    struct node *start,*temp;
    start=(node *)malloc(sizeof(node));
    temp=start;
    temp->next=NULL;
    while(choice!=4)
     {
              printf("enter choice number\n");
              printf("1)add an element\n2)delete an element\n3)display list\n4)to exit");
              scanf("%d",&choice) ;
              
             if(choice==1)
                  {    printf("enter element to be added");
                       scanf("%d",&num);
                       incert(num,temp);
                        printf("\n");
                  }
             else if(choice==2)
             {
                printf("enter the data to be deleted");
                scanf("%d",&num);
                del(num,start);
             }
        
             else if(choice==3)
                      display(start);
    
             else if(choice==4)
                      break;


             else
                      printf("wrong choice");
     }
}

[Subsonics]

I don't really follow what you are doing in your del function. The else clause assumes that you have found the target node that you are about to delete, why are you allocating a new node there? It's also a memory leak by the way because you immediately assign a new value to t after you have allocated memory to it.

All you need to do, fitting with your existing code is to hold on to the present node->next and then re-link node->next->next to node->next. Example:

void *target = pointer->next;
pointer->next = pointer->next->next;
free(target);

You should refer to your node data type as struct node btw, not just node in function prototypes and so on.