Thread: linked lists inserting problem

Hi,
I am making a long integer arthimetic calculator that performs +and*. I am adding an element and then printing the node.The problem I am having is that I can the value I inserted but I also get random garbage in front that I never inserted.

For example if I insert 10 I get 0 -38 10
My code is:

Code:

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


#include <string.h>
#include <ctype.h>
#define FALSE 0

typedef struct node
{
    int integerone;
    struct node * link;
} list_head;
/* Printing the list Contents */

void printList(list_head*head){
  list_head*temp=head;
  while(temp){
    printf("%d  " ,  temp->integerone);
    temp=temp->link;
  }

}

void Menu(int *choice) {

    char    local;
    printf("\n1.Insert first number\n");
     printf("2. Insert second number\n");
     printf("3. Add numbers\n");
     printf("4. Multiply numbers\n");
     printf("5. Process file\n");
     printf("6. Quit\n");
    printf("Enter Option: ");
    do {
	local = getchar ();
    } while (isdigit ((unsigned char) local) == FALSE);
    *choice = (int) local - '0';
}



int insert_to_list(list_head**head,int digit){
    list_head *tmp;
    tmp=NULL;
     tmp = malloc(sizeof(list_head));

   tmp->integerone=digit;
   tmp->link=NULL;

   if(*head==NULL){
      *head=tmp;
   }
 	 else{
	    list_head*temp=*head;
                   while(temp->link!=NULL){
                   temp=temp->link;}
                   temp->link=tmp;
                  return *head;
       }
  }



//allocate memory for a new list header
list_head *create_list(void){
list_head*p=NULL;
p=malloc(sizeof(list_head));

		p->link=NULL;

return p;
}
int main(void){
list_head *head=NULL;
int choice;
char c;

head=create_list();

  do {
	Menu (&choice);
	switch (choice) {
	    case 1:
		 printf("1. Insert first number\n");
	                scanf("%c",&c);
                                do{

		     head=insert_to_list(&head,c-'0');
                                }while((c = getchar()) != '\n');
                     break;
	    case 2:
		printf("2.print list\n");
                                    printList(head);

		break;
	    case 3:
		printf("3. Add numbers\n");

		break;

	    case 4:
		break;
 		printf("4. Multiply numbers\n");

 	    case 5:
		printf("5. Process file\n");
		break;

	    case 6:
		break;
	    default:
		printf ("Invalid menu choice - try again\n");
		break;
	}
    } while (choice != 6);

}

does anybody have an idea what is wrong.

thanks for the help but there is one more problem it still prints
-38 . I don't undertand where is -38 coming from.

Outside of tons of gross coding errors, the following lines irked me the most

Code:

list_head *create_list(void){
  list_head*p=NULL;  /*this sort of irks me, but whatever*/
  p=malloc(sizeof(list_head));

  p->link=NULL;
 /*You need to allocate memory for p->link*/

 /*now p has to point to the next node in the list*/
  return p;
}

First, you don't check malloc() for NULL. However, that is the least of your immediate worries in this case. You allocate memory for p, but not for p->link. On top of that, you need to then have p point to p->link (ie p = p->link).

Second, the prototype for getchar() is

Code:

int getchar(void);

In other words, don't go

Code:

char c;

c = getchar();

It should be
int c;

Third, scanf() blows. If you must use it, at least check for junk values.