Creating and reversing a linked list

Here is my program which creates a linked list and reverses it:

```
#include
#include
struct node {
int data;
struct node *next;
};
struct node *list=NULL;
struct node *root=NULL;
static int count=0;
struct node *create_node(int);//function to create node
void travel_list(void);
void create_list(int);
void reverse_list(void);
int main()
{
int i, j, choice;
printf("Enter a number this will be root of tree\n");
scanf("%d", &i);
create_list(i);
printf("Enter 1 to enter more numbers \n 0 to quit\n");
scanf("%d", &choice);
while (choice!=0){
printf("Enter a no for link list\n");
scanf("%d",&i);
// printf("going to create list in while\n");
create_list(i);
travel_list();
printf("Enter 1 to enter more numbers \n 0 to quit\n");
scanf("%d", &choice);
}
printf("reversing list\n");
reverse_list();
travel_list();
}

// end of function main
void create_list (int data)
{
struct node t1,t2;
//printf("in fucntion create_list\n");
t1=create_node(data);
t2=list;
if( count!=0)
{
while(t2->next!=NULL)
{
t2=t2->next;
}
t2->next=t1;
count++;
}
else
{
root=t1;
list=t1;
count++;
}
}
struct node *create_node(int data)
{
struct node *temp;
temp = (struct node *)malloc(sizeof(struct node));
temp->data=data;
temp->next=NULL;
// printf("create node temp->data=%d\n",temp->data);
// printf("the adress of node created %p\n",temp);
return temp;
}
void travel_list(void )
{
struct node *t1;
t1=list;
printf("in travel list\n");
while(t1!=NULL)
{
printf("%d-->",t1->data);
t1=t1->next;
}
printf("\n");
}
void reverse_list(void)
{
struct node t1,t2,*t3;
t1=list;
t2=list->next;
t3=list->next->next;
int reverse=0;
if(reverse==0)
{
t1->next=NULL;
t2->next=t1;
t1=t2;
t2=t3;
t3=t3->next;
reverse++;

}

while(t3!=NULL)
{

t2->next=t1;
t1=t2;
t2=t3;
list=t1;

#include
#include
struct node {
    int data;
    struct node *next;
};
struct node *list=NULL;
struct node *root=NULL;
static int count=0;

Don't store data in global variables. It makes your code unreusable and harder to follow.

struct node *create_node(int);//function to create node
void travel_list(void);
void create_list(int);
void reverse_list(void);
int main()
{
    int i, j, choice;

Using variables like i and j only make sense if used in the sense of indexes. Otherwise, the code just gets harder to read. Choice is also not very informative.

printf("Enter a number this will be root of tree\n");
    scanf("%d", &i);
    create_list(i);
    printf("Enter  1 to enter more numbers \n 0 to quit\n");
    scanf("%d", &choice);
    while (choice!=0){
     printf("Enter a no for link list\n");
        scanf("%d",&i);

Use consistent indentation. Otherwise things will go downhill fast.

//  printf("going to create list in while\n");

Don't leave dead code in your code, that's what source control is for.

create_list(i);
        travel_list(); 
    printf("Enter  1 to enter more numbers \n 0 to quit\n");
    scanf("%d", &choice);

Deja vu. Why isn't the previous instance doing the same thing done in the loop?

}
    printf("reversing list\n");
     reverse_list();
     travel_list();
 }

// end of function main
void create_list (int data)

This function appends to the end of a list, it doesn't create it. Use function names that indicate what is really happening.

{
 struct node *t1,*t2;

t1 and t2 are very uninformative variable names.

//printf("in fucntion create_list\n");
 t1=create_node(data);
 t2=list;
 if( count!=0)

This is the only place that count is used. Check whether list is null instead.

{
   while(t2->next!=NULL)
   {
   t2=t2->next;
   }
 t2->next=t1;
 count++;
 }
 else 
  {
   root=t1;

You don't ever seem to do anything with root.

list=t1;
   count++;
  }
}
struct node *create_node(int data)
{
    struct node *temp;

The new node isn't really temporary

temp = (struct node *)malloc(sizeof(struct node));
        temp->data=data;
    temp->next=NULL;
  //      printf("create node temp->data=%d\n",temp->data);
//  printf("the adress of node created %p\n",temp);
    return temp;
}
void travel_list(void )
{
 struct node *t1;
 t1=list;
 printf("in travel list\n");
 while(t1!=NULL)
 {
 printf("%d-->",t1->data);
 t1=t1->next;
 }
 printf("\n");
}
void reverse_list(void)
{
    struct node *t1,*t2,*t3;

This piece of code would be way easier to follow if you used real names

t1=list;
    t2=list->next;
    t3=list->next->next;

This is going to fail for lists shorter then three elements

int reverse=0;
   if(reverse==0)

This will always be true since you just assigned reverse = 0.

{
    t1->next=NULL;
    t2->next=t1;
    t1=t2;
    t2=t3;
    t3=t3->next;
    reverse++;

You never use reverse again

}

    while(t3!=NULL)
     {

     t2->next=t1;
    t1=t2;
    t2=t3;
    list=t1;
    travel_list();
    t3=t3->next;
    }
    t2->next=t1;
    list=t2;
}

My version of reverse_list (untested)

struct node * reverse_list(struct node * list)
{
    struct node *previous, *current;
    previous = NULL;
    current = list;
    while(current)
    {
        struct node * next = current->next;
        current->next = previous;
        previous = current;
        current = next;
    }
    return previous;
}

}

StackExchange Code Review Q#3018, answer score: 7