Thread: what are the bugs in this code..please help me.

This code is intended to merge, two sorted, linked lists into a single sorted, linked list: it is supposed to take two lists as input and destructively modify them so that at the end, they form a single, sorted, linked list in memory.
What are bugs in the code?

Code:

typedef struct link {
char *data;
struct link *next;
} list;


list *merge(list *input1, list *input2) {
list *output = NULL, *tail, *next;
do {
if(strcmp(input1->data, input2->data) <= 0) {
next = input1;
input1 = input1->next;
} else {
next = input2;
input2 = input2->next;
}
if (output == NULL) {
output = tail = next;
} else {
tail->next = next;
tail = tail->next;
}
} while (input1 != NULL && input2 != NULL);
if (input1 != NULL) tail->next = input1;
else tail->next = input2;
return output;
}

what compiler i need to use to compile this code?

A C compiler, obviously. Even then, your code is incomplete as it does not include the appropriate header files.

How did you get this code in the first place?

I'm sorry if this sounds harsh, but have you considered that learning to do something actually means that you have to practice, rather than asking someone else to do it for you?

Indent style:

Code:

typedef struct link {
    char *data;
    struct link *next;
} list;


list *merge(list *input1, list *input2) {
    list *output = NULL, *tail, *next;
    do {
	if(strcmp(input1->data, input2->data) <= 0) {
	    next = input1;
	    input1 = input1->next;
	} else {
	    next = input2;
	    input2 = input2->next;
	}
	if (output == NULL) {
	    output = tail = next;
	} else {
	    tail->next = next;
	    tail = tail->next;
	}
    } while (input1 != NULL && input2 != NULL);
    if (input1 != NULL) tail->next = input1;
    else tail->next = input2;
    return output;
}

Note that you will want to avoid mixing tabs and spaces, as tabs can be different size on different systems. [The above is indented using XEmacs and C-style "stroustrup", using the M-X indent-region command].



--
Mats

Originally Posted by me001

Please post some C tutorials

We're not your lackeys! Search the web yourself!

QuantumPete

Bug 1 :
line 8: variable 'NULL' not found
'list *output = NULL, *tail, *next'
aborting compile

That's because the appropriate headers (<stddef.h> and also <string.h>) were not included. NULL is from <stddef.h>, though <string.h> may include it as well.

It looks like you need to refresh your knowledge of the C preprocessor. You along with several other people here. It's like a rash.