unable to reverse a linked list - c language - c

Question

i have a simple linked list with a string, int, and next pointer in each node.
all the other linked list functions works (pop, push, delete node, etc.), but the reverse function just duplicate my node.
here is my code:
personNode* reverseList(personNode* head)
{
personNode* curr = head;
personNode* previous = NULL;
personNode* next = NULL;
while (curr != NULL)
{
next = curr->next;
curr->next = previous;
previous = curr;
curr = next;
}
head = previous;
printf("Line reversed!");
return head;
}
the results are:
Before "reversing":
and after:
(Here is The whole code:)
#include <stdio.h>
#define STR_LEN 21
typedef struct personNode
{
char name[STR_LEN];
int age;
char friends[3][STR_LEN];
struct personNode* next;
}personNode;
int recursiveLength(personNode* head, int counter);
void createPerson(char name[], int age, char friends[3][STR_LEN], personNode* head);
void link(personNode* head, personNode* toLink);
char* iHaveFriends(personNode* guest, personNode* head);
int addBehindFriend(char* friendName, personNode* guest, personNode* head);
void removePersonByName(char name[], personNode* head);
void addToListTop(personNode* VIP, personNode* head);
void search(personNode* head, char name[]);
personNode* reverseList(personNode* head);
void freeList(personNode* head);
int main(void)
{
int i = 0;
int choice = 0;
char name[STR_LEN] = { 0 };
int age = 0;
char friends[3][STR_LEN];
personNode* head = (personNode*)malloc(sizeof(personNode));
head->next = NULL;
while (choice != 7)
{
printf("\n\nWelcome to MagshiParty Line Management Software!\nPlease enter your choice from the following options :\n1 - Print line\n2 - Add person to line\n3 - Remove person from line\n4 - VIP guest\n5 - Search in line\n6 - Reverse line\n7 - Exit\n");
scanf("%d", &choice);
switch (choice)
{
case 1:
{
printf("%d people in line: \n", recursiveLength(head, 0));
recursivePrint(head);
break;
}
case 2:
{
printf("Welcome guest!");
printf("\nEnter name: ");
getchar();
scanf("%[^\t\n]s", name);
getchar();
printf("\nEnter age: ");
scanf("%d", &age);
printf("Enter names of 3 friends: ");
for (i = 0; i < 3; i++)
{
printf("\nFriend %d: ", i + 1);
getchar();
scanf("%[^\t\n]s", friends[i]);
getchar();
}
createPerson(name, age, friends, head);
break;
}
case 3:
{
printf("Enter name to remove: ");
getchar();
scanf("%[^\t\n]s", name);
getchar();
removePersonByName(name, head);
break;
}
case 4:
{
printf("VIP GUEST!\n");
printf("Enter name: ");
getchar();
scanf("%[^\t\n]s", name);
getchar();
printf("Enter age: ");
scanf("%d", &age);
personNode* newNode = (personNode*)malloc(sizeof(personNode));
newNode->age = age;
strcpy(newNode->name, name);
newNode->next = NULL;
addToListTop(newNode, head);
break;
}
case 5:
{
printf("Enter name to search: ");
getchar();
scanf("%[^t\n]s", name);
getchar();
search(head, name);
break;
}
case 6:
{
head = reverseList(head);
break;
}
case 7:
{
freeList(head);
printf("Goodbye!");
break;
}
default:
{
freeList(head);
printf("Goodbye!");
break;
}
}
}
getchar();
getchar();
return 0;
}
int recursiveLength(personNode* head, int counter)
{
personNode* curr = head;
if (head->next == NULL)
{
return counter;
}
else
{
if (curr->next != NULL)
{
counter++;
recursiveLength(curr->next, counter);
}
else
{
return counter;
}
}
}
int recursivePrint(personNode* head)
{
personNode* curr = head;
if (head->next == NULL)
{
return 0;
}
else
{
if (curr->next != NULL)
{
printf("Name: %s, Age: %d \n", curr->name, curr->age);
recursivePrint(curr->next);
}
else
{
return 0;
}
}
}
void createPerson(char name[], int age, char friends[3][STR_LEN], personNode* head)
{
int i = 0;
personNode* newNode = (personNode*)malloc(sizeof(personNode));
for (i = 0; i < 3; i++)
{
strcpy((newNode->friends[i]), friends[i]);
//printf("inserted = %s , bimkom - %s\n", (newNode->friends[i]), friends[i]);
}
newNode->age = age;
strcpy(newNode->name, name);
newNode->next = NULL;
link(head, newNode);
}
void link(personNode* head, personNode* toLink)
{
personNode* curr = head;
int i = 0;
if (head->next == NULL) // first node - list empty
{
//printf("First!");
for (i = 0; i < 3; i++)
{
strcpy((head->friends[i]), (toLink->friends[i]));
//printf("inserted = %s , bimkom - %s\n", (head->friends[i]), toLink->friends[i]);
}
//curr->next = malloc(sizeof(personNode));
curr->age = toLink->age;
strcpy(curr->name, toLink->name);
head->next = toLink;
//curr->next = NULL;
}
else
{
char foundFriend[STR_LEN] = { 0 };
strcpy(foundFriend, iHaveFriends(toLink, head));
//printf("returned from iHaveFriends: %s", foundFriend);
if (!addBehindFriend(foundFriend, toLink, head))
{
//printf("addBehindFriend Failed!");
while (curr->next != NULL)
{
curr = curr->next;
}
//curr->next = malloc(sizeof(personNode));
for (i = 0; i < 3; i++)
{
*(head->friends[i]) = toLink->friends[i];
}
curr->age = toLink->age;
strcpy(curr->name, toLink->name);
curr->next = toLink;
}
}
}
char* iHaveFriends(personNode* guest, personNode* head)
{
personNode* curr = head;
int i = 0;
char foundFriend[STR_LEN] = { 0 };
while (curr->next != NULL)
{
for (i = 0; i < 3; i++)
{
if (strcmp(curr->name, guest->friends[i]) == 0)
{
//printf("\nMATCH: %s, %s, %s\n", foundFriend, guest->friends[i], curr->name);
strcpy(foundFriend, guest->friends[i]);
}
else
{
//printf("\nProblem in friend Check!, compared: %s, %s\n", curr->name, guest->friends[i]);
}
}
//printf("\nName: %s", curr->name);
curr = curr->next;
}
//printf("\nReturning: %s", foundFriend);
return foundFriend;
}
int addBehindFriend(char* friendName, personNode* guest, personNode* head)
{
//printf("\nrecived: %s, %s\n", friendName, guest->name);
personNode* curr = head;
personNode* temp = 0;
char foundFriend[STR_LEN] = { 0 };
int flag = 0;
while (curr->next != NULL)
{
if (strcmp(friendName, curr->next->name) == 0)
{
flag = 1;
temp = curr->next;
curr->next = guest;
guest->next = temp;
}
else
{
//printf("%s, %s\n", friendName, curr->next->name);
}
curr = curr->next;
}
return flag;
}
void removePersonByName(char name[], personNode* head)
{
personNode* curr = head;
int flag = 0;
while (curr->next != NULL)
{
if (strcmp(curr->next->name, name) == 0 && curr->next->next != NULL)
{
flag = 1;
curr->next = curr->next->next;
break;
}
curr = curr->next;
}
if (flag)
{
printf("%s removed from line", name);
}
else
{
printf("%s not in line", name);
}
}
void addToListTop(personNode* VIP, personNode* head)
{
personNode* tmp = (personNode*)(malloc(sizeof(personNode)));
tmp->age = head->age;
strcpy(tmp->name, head->name);
tmp->next = head->next;
head->age = VIP->age;
strcpy(head->name, VIP->name);
head->next = tmp;
//VIP->next = tmp;
}
void search(personNode* head, char name[])
{
personNode* curr = head;
int flag = 0;
while (curr->next != NULL)
{
if (strcmp(curr->name, name) == 0)
{
flag = 1;
break;
}
curr = curr->next;
}
if (flag)
{
printf("%s found in line", name);
}
else
{
printf("%s not in line", name);
}
}
personNode* reverseList(personNode* head)
{
personNode* curr = head;
personNode* previous = NULL;
personNode* next = NULL;
while (curr != NULL)
{
next = curr->next;
curr->next = previous;
previous = curr;
curr = next;
}
head = previous;
printf("Line reversed!");
return head;
}

Answer 1

Your reverse function logic seems fine. There's a problem in your recursiveprint function, so here you go, try this simple one:
void print(struct personNode *head)
{
struct personNode *temp = head;
while(temp != NULL)
{
    printf("%s  ", temp->name);   
    temp = temp->next; 
}
}   

Answer 2

The Reverse function was not working as it should on my local machine.
It was hard to debug it so I prefered to rewrite it.
Reverse function works like this :
static personNode * reverse(struct personNode *head)
{
struct personNode* localHead = NULL;
struct personNode* temp;
struct personNode* remainingHead;
while (head != NULL)
{
remainingHead = head->next;
temp = localHead;
localHead = head;
localHead->next = temp;
head = remainingHead;
}
return localHead;
}
Regarding youre recursive print function
I am checking the head for null , not the next pointer.
int recursivePrint(personNode* head)
{
personNode* curr = head;
if (head == NULL)
{
return 0;
}
else
{
if (curr != NULL)
{
printf("Name: %s, Age: %d \n", curr->name, curr->age);
recursivePrint(curr->next);
}
else
{
return 0;
}
}
}