Thread: function questions

I take it this is with reference to http://cboard.cprogramming.com/showthread.php?t=77576
The create_list() function in that code does nothing useful, it just creates a junk node at the head of the list.

A true empty list is
list_head *head=NULL;

And your insert_to_list() function already knows how to insert into an empty list with the if(*head==NULL) test.

I have one more question. I am making a calulator for long intergers the operations I can perform are + and *;

I am having problem making an add function. I don't know what to do I am lost.
The functions that I am stuck in are:

int add_two_digits(int d1, int d2, int *carry_in, int * result, int *carry_out);
list_head * add_two_numbers (list_head N1, list_head N2);

I tried to do the formating of the code but since I bring from textpad to this bord the formating becomes horrible.

The code that I have now is:

Code:

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

#define FALSE 0
char c = '\0';
int currentChar = 0;
int numOfCharsInC = 0;

typedef struct node
{
  int integerone;
  struct node * link;
} list_head;
list_head*list1,*list2,*result;

//Concating the 2 lists together
list_head * concat(list_head *p,list_head *q)
{
	list_head *x,*r;
	if (p==NULL)
	   r=q;

	if (q==NULL)
	     r=p;
	else
	{
	    x=p;
      	     r=x;
      	while(x->link!=NULL)
	    x=x->link;
     	    x->link=q;
	}
    return(r);
}

//Inserting in the list
int insert_to_list(list_head**head,int digit){
  list_head *newNode= malloc(sizeof(list_head));

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

  if(*head==NULL){
    *head=newNode;
return 1;
  }
  else{
    list_head*temp=*head;
    while(temp->link!=NULL){
      temp=temp->link;

    }
    temp->link=newNode;

  }
  return 0;
}

//Menu choices
void options(){
    printf("\n1. Insert first number\n");
    printf("1. 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: ");
	scanf("%c",&c);
    fflush(stdin);
}

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

}
//Reverses the list
list_head *reverse_list(list_head *head){
	list_head  *p,*q,*r;
	p=head;
	q=NULL;

	while(p!=NULL)
	{
	    r=q;
	    q=p;
	    p=p->link;
	    q->link=r;
	}
	head = q;
	printList(head);
}

//Add two digits <!!!!!THIS IS THE FUNCTION THAT I NEED HELP WITH!!!!!!!>

int add_two_digits(int d1, int d2, int *carry_in, int * result, int *carry_out){
*carry_in=0;

for (i=0;; i++) {
	*result =*result = d1+d2+*carry_in;
                  if(result>=10){
	 *result=*result-10;
	 *carry_out=1;
	}
	else{
	   *carry_out=0;
	}

}



//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;
}

//Main function
int main(void){
     options();
      while (c!='6'){
         while ((currentChar = getchar()) != '\n' && currentChar != EOF){
 	if(numOfCharsInC==0) {
               	    c = currentChar;
	}
	numOfCharsInC++;
        }

     if(c=='1'){
         fflush(stdin);
         printf("\n1. Insert first number\n");
         scanf("%c",&c);
         fflush(stdin);
         do{
             insert_to_list(&list1,c-'0');

         } while((c = getchar()) != '\n');
         numOfCharsInC = 0;
         options();
    }

     else if(c=='2'){
          fflush(stdin);
          printf("\n2. Insert second number\n");
          scanf("%c",&c);
          fflush(stdin);
          do{
	  insert_to_list(&list2,c-'0');
              } while((c = getchar()) != '\n');
	                   
          numOfCharsInC = 0;
         options();

       }


     else if (c== '3'){
		fflush(stdin);
        printf("\n3. Add numbers\n");
		numOfCharsInC = 0;
		options();

	 }

     else if(c== '4'){
		fflush(stdin);
        printf("\n4. Multiply numbers\n");
        numOfCharsInC = 0;
		options();

	 }

     else if(c=='5'){
		fflush(stdin);
        printf("\n5. Process file\n");
        numOfCharsInC = 0;
		options();

     }
     else if(c=='6'){
		fflush(stdin);
		numOfCharsInC = 0;
		options();
        break;
     }
     else{

        printf ("Invalid menu choice - try again\n");
        break;
     }
  }
  return 0;
}

Thanks alot for help. I really appreciate it.
Sara

Um...uh...hmm...ahh...

</offtopic>





So what exactly is wrong? The algorithm? The code? Segfault?