Completely new to C, im trying to make a linked list in C that sorts a pre existing char array alphabetically. Each char is assigned an index. So the listInsert function should insert each string into the linked list and sort them alphabetically, so that when listPrintForward is called, the items in the linked list will be printed alphabetically.
Here is the current output when i run the program.
https://i.stack.imgur.com/KmKAi.jpg
INSERT:
bravo oscar romeo delta whisky alpha
foxtro sierra yankee lima echo
golf november victor charlie mike
zulu tango kilo quebec hotel
juliet xray papa uniform india
FORWARD: 0 entries
india uniform papa xray juliet hotel
quebec kilo tango zulu mike
charlie victor november golf echo
lima yankee sierra foxtrot alpha
whisky delta romeo oscar bravo
As you can see all my listInsert function current does is insert them into a linked list (I think) and when the printForward function is called, it reverses the contents of the linked list, when it should print the contents of the linked list in alphabetical order.
The output I want to happen should be :
INSERT:
bravo oscar romeo delta whisky alpha
foxtro sierra yankee lima echo
golf november victor charlie mike
zulu tango kilo quebec hotel
juliet xray papa uniform india
FORWARD: 0 entries
alpha bravo charlie delta echo foxtrot
golf hotel india juliet kilo
lima mike november oscar papa
quebec romeo sierra tango uniform
victor whisky xray yankee zulu
Does anyone know how to fix this or what I'm doing wrong? Here is the full code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define SUCCESS 0
#define FAIL 1
char *phonetic[] = { "alpha", "bravo", "charlie", "delta", "echo", "foxtrot",
"golf", "hotel", "india", "juliet", "kilo", "lima", "mike",
"november", "oscar", "papa", "quebec", "romeo", "sierra",
"tango", "uniform", "victor", "whisky", "xray", "yankee",
"zulu" };
unsigned char indexes[] = { 1, 14, 17, 3, 22, 0, 5, 18, 24, 11, 4, 6, 13, 21,
2, 12, 25, 19, 10, 16, 7, 9, 23, 15, 20, 8 };
// represents an entry in the linked-list
struct listEntry
{
char *data_p; // pointer to the entry's string
struct listEntry *prev_p; // pointer to previous entry in the linked-list
struct listEntry *next_p; // pointer to next entry in the linked-list
};
// represents the linked-list
struct list
{
int entryCount; // number of entries present in the linked-list
struct listEntry *head_p; // pointer to the first entry in the list
struct listEntry *tail_p; // pointer to the last entry in the list
};
// Dynamically allocate & initialise an empty linked list
int listCreate(struct list** list_p2)
{
// allocate struct list from heap
*list_p2 = (struct list*) malloc(sizeof(**list_p2));
if (*list_p2 != NULL)
{
// zero-initialize the list structure
memset(*list_p2, 0, sizeof(**list_p2));
return SUCCESS;
}
return FAIL;
}
// Free all entries in the linked-list and the list structure
int listDestroy(struct list *list_p)
{
if (list_p != NULL)
{
struct listEntry *entry_p = list_p->head_p;
while (entry_p != NULL)
{
struct listEntry *next_p = entry_p->next_p;
// free the current entry
free(entry_p);
// move to the next entry
entry_p = next_p;
}
// free list structure
free(list_p);
}
return FAIL;
}
// Traverse the linked-list from head to tail printing out
// the string data from each list entry
int listPrintForward(struct list *list_p)
{
if (list_p)
{
struct listEntry *entry_p = list_p->head_p;
int count = 0;
printf("FORWARD: %d entries\n", list_p->entryCount);
while (entry_p != NULL)
{
if ((count > 0) && (count % 5 == 0))
{
printf("%s\n", entry_p->data_p);
}
else
{
printf("%s ", entry_p->data_p);
}
if (entry_p == list_p->tail_p)
printf("\n");
entry_p = entry_p->next_p;
fflush(stdout);
count++;
}
return SUCCESS;
}
return FAIL;
}
// Traverse the linked-list from tail to head printing out
// the string data from each list entry
int listPrintReverse(struct list *list_p)
{
if (list_p)
{
struct listEntry *entry_p = list_p->tail_p;
int count = 0;
printf("REVERSE: %d entries\n", list_p->entryCount);
while (entry_p != NULL)
{
if ((count > 0) && (count % 5 == 0))
{
printf("%s\n", entry_p->data_p);
}
else
{
printf("%s ", entry_p->data_p);
}
if (entry_p == list_p->head_p)
printf("\n");
entry_p = entry_p->prev_p;
fflush(stdout);
count++;
}
return SUCCESS;
}
return FAIL;
}
// Insert the given string into the linked-list such that the
// entries in the linked-list are in alphabetical order
int listInsert(struct list *list_p, char *string_p)
{
struct listEntry *temp;
temp=(struct listEntry *)malloc(sizeof(struct listEntry));
temp->data_p = string_p;
if (list_p->head_p == NULL)
{
//List is Empty
list_p->head_p = temp;
temp->next_p = NULL;
}
else
{
temp->next_p =list_p->head_p;
list_p->head_p = temp;
}
return FAIL;
}
int main(int argc, char **argv)
{
struct list *list_p = NULL;
(void) argc;
(void) argv;
if (listCreate(&list_p) == SUCCESS)
{
unsigned int count;
// insert every word in the phonetic alphabet into the
// linked-list.
printf("INSERT:\n");
for (count = 0; count < sizeof(indexes); count++)
{
if ((count > 0) && (count % 5 == 0))
{
printf("%s\n", phonetic[indexes[count]]);
}
else
{
printf("%s ", phonetic[indexes[count]]);
}
listInsert(list_p, phonetic[indexes[count]]);
}
printf("\n");
// print out the list in alphabetical order
listPrintForward(list_p);
// print out the list in reverse alphabetical order
listPrintReverse(list_p);
// Destroy the linked list and free all associated memory
listDestroy(list_p);
}
return SUCCESS;
}
