Linked Lists in C

[RobMunfy]

Hi guys, having a bit of trouble with my printlist function (it prints out all 1's, instead of the values that i enter):

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

typedef struct L {
	int data;
	struct L *next;
} list;

list *insertList( int hd, list *tl ) {
	list *t = malloc( sizeof( list ) ) ;
	t->data = hd ;
	t->next = tl ;
	return t ;
}

list *somelist( void ) {
	list *h = NULL ;
	int i=1;
	int c;
	while(c=getchar()!='.') {
		h=insertList( c, h );
		i++;
	}
	return h ;
}

void printlist(list *head) {
     int i;
     list *current = head;
     
     while(current!=NULL) {
        printf("%d", current->data);
		current=current->next;
	}	
}

int length(list *head) {
	list *current = head;
	int count = 0;
	while (current != NULL) {
		count++;
		current = current->next;
	}
	printf("%d\n", count);
	return count;
}

int main(void) {
	
	
	list *z=somelist();
	length(z);
	printlist(z);
	
	return 0;
}

So if i input:

12345

.

The output will be:

5
11111

Any help would be great.

Cheers, Rob

 

[Eriedor]

Forgive me as it's been awhile since I've done C but should

current=current->next;

be

current=current.next;

as it's a struct you are accessing not an object.

 

[Inquisitor]

list *somelist( void ) {
	list *h = NULL ;
	int i=1;
	int c;
	while([B][COLOR="Red"]c=getchar()!='.'[/COLOR][/B]) {
		h=insertList( c, h );
		i++;
	}
	return h ;
}

You need to put parentheses around c = getchar(). What it's currently doing is evaluating getchar() != '.' and assigning the result – which is 1 as long as you don't input a period – to c.

Forgive me as it's been awhile since I've done C but should

current=current->next;

be

current=current.next;

as it's a struct you are accessing not an object.

Nope, because current is a pointer, so the -> operator is needed to dereference it.

 

[RobMunfy]

list *somelist( void ) {
	list *h = NULL ;
	int i=1;
	int c;
	while([B][COLOR="Red"]c=getchar()!='.'[/COLOR][/B]) {
		h=insertList( c, h );
		i++;
	}
	return h ;
}

Hey, that works, but it still doesn't print out the right result.

It prints out:

Input: 1.
Output: 49

Input: 1
         .
Output: 1049

Input: 2.
Output: 50

Any ideas?

 

[RobMunfy]

sorry, being stupid, can't use getchar and put into an int!

 

[Inquisitor]

edit: beaten

That's because you're storing them and displaying them as integers.

What you need to do instead is either store them as characters or convert them to just before displaying them:

typedef struct L {
	[COLOR="Red"][B]char[/B][/COLOR] data;
	struct L *next;
} list;

/* snip */

void printlist(list *head) {
	int i;
	list *current = head;
	
	while(current!=NULL) {
		printf("[COLOR="Red"][B]%c[/B][/COLOR]", current->data);
		current=current->next;
	}	
}

…or…

while(current!=NULL) {
	printf("[COLOR="Red"][B]%c[/B][/COLOR]", [COLOR="Red"][B](char)[/B][/COLOR]current->data);
	current=current->next;
}