while loop

why only the first Iteration workin alright ?

Code:

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

struct Node
{
	int val;
	struct Node *next;
} ;

typedef struct Node Node ;


	void addNode(Node *head,Node *tail)
	{
		Node *current, *temp;
		char Continue='y';
		head=(Node*)malloc(sizeof(Node));
		head->val=1;
		current=head;
		do
		{
			printf("continue?\n");
			scanf("%c",&Continue);
			temp=(Node*)malloc(sizeof(Node));
			printf("value=?\n");
			scanf("%d",&(temp->val));
			current->next=temp;
			current=current->next;
		}
		while(Continue!='n');
	}



void main()
{
	Node *head=NULL, *tail=NULL;

	addNode(head,tail);

}

TNX

#1

Code:

do
{
    ...
    scanf("%c",&Continue);
    ...
    scanf("%d",&(temp->val));
}
while(Continue!='n');

The problem is that %c in the scanf call will read a newline leftover in the input stream from the previous loops read of the integer value. Simplest solution there is to add a space in front of the %c format specifier which will tell the scanf call to ignore leading whitespace.

Code:

scanf(" %c",&Continue);
       ^ there's a space there now

#2

Code:

head=(Node*)malloc(sizeof(Node));

...

temp=(Node*)malloc(sizeof(Node));

Avoid casting the return value of the malloc call.


#3 You should be setting the next pointer of the newly allocated node to null after you create it, also you head node's next pointer.



#4

Code:

void main()

main returns int not void.



#5

Code:

void addNode(Node *head,Node *tail)
{
    ...
}

void main()
{
	Node *head=NULL, *tail=NULL;

	addNode(head,tail);

}

If you expect to actually do anything with those head/tail pointers in main after the call to addNode then you'll need to change your addNode function to accept pointer-to-pointer-to-Node arguments rather than just simple pointer-to-Node arguments.

ok... thank you very much !