how to add a newly created node to linklist? - c

Question

here is my code, i can only add the node to the head of the linklist, but how to append to the tail to the linklist? thanks
struct recordNode {
char name[256];
char event[128]; /
float time;
struct recordNode* next;
};
struct recordNode* temp;
struct recordNode* aRecordPointer = NULL;
struct recordNode* createRecord(char* name, char* event, float time) {
temp = (struct recordNode*)malloc(sizeof(struct recordNode));
strcpy(temp->name, name);
strcpy(temp->event, event);
temp->time = time;
/* link up */
if (aRecordPointer == NULL) {
aRecordPointer = temp;
temp->next = NULL;
} else {
temp->next = aRecordPointer;
aRecordPointer = temp;
}
return aRecordPointer;
}
int main() {
struct recordNode* record = createRecord("1abc", "abc", 12.25);
record = createRecord("2abc", "abc", 25.98);
record = createRecord("3abc", "abc", 52.60);
}
/* now result:
3abc abc 12.25
2abc abc 25.98
1abc abc 52.60
needed result:
1abc abc 52.6
2abc abc 25.98
3abc abc 12.25
*/

Answer 1

Assuming that aRecordPointer is your pointer to the head (first) element of list, you need to iterate the list from head to tail (last).
struct recordNode* createRecord(char* name, char* event, float time){
temp = (struct recordNode*)malloc(sizeof(struct recordNode));
strcpy(temp->name, name);
strcpy(temp->event, event);
temp->time = time;
temp->next = NULL;
if (aRecordPointer == NULL) {
aRecordPointer = temp;
}
else {
struct recordNode* pLast = aRecordPointer;
/* find the last element */
while(pLast->next != NULL) {
pLast = pLast->next;
}
/* get linked */
pLast->next = temp;
}
return aRecordPointer;
}

Answer 2

Assuming that aRecordPointer is a pointer to the last Node, modify your code as below:
struct recordNode* createRecord(char* name, char* event, float time)
{
temp = (struct recordNode*)malloc(sizeof(struct recordNode));
strcpy(temp->name, name);
strcpy(temp->event, event);
temp->time = time;
//I have added this line as well.
temp->next = NULL;
/* link up */
if (aRecordPointer == NULL)
{
aRecordPointer = temp;
}
else
{
aRecordPointer->next = temp;
aRecordPointer = temp;
}
return aRecordPointer;
}
Also note that you should always have a pointer to Head (First Node) in order to traverse the linked list later.

Answer 3

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
void Traverse();
struct recordNode {
char name[256];
char event[128];
float time;
struct recordNode* next;
};
struct recordNode* temp;
struct recordNode* aRecordPointer = NULL;
struct recordNode* createRecord(char* name, char* event, float time) {
struct recordNode * ToTraverseTheLinkedList;
temp = (struct recordNode*)malloc(sizeof(struct recordNode));
strcpy(temp->name, name);
strcpy(temp->event, event);
temp->time = time;
temp->next = NULL;
/* link up */
if (aRecordPointer == NULL) {
aRecordPointer = temp;
//temp->next = NULL;
}
else
{
ToTraverseTheLinkedList = aRecordPointer;
while(ToTraverseTheLinkedList->next != NULL)
{
ToTraverseTheLinkedList = ToTraverseTheLinkedList ->next;
}
ToTraverseTheLinkedList->next = temp;
}
return aRecordPointer;
}
int main() {
createRecord("1abc", "abc", 12.25);
//Traverse();
createRecord("2abc", "abc", 25.98);
createRecord("3abc", "abc", 52.60);
Traverse();
}
void Traverse()
{
struct recordNode * temp;
temp = aRecordPointer;
while(temp != NULL)
{
printf("%s\n",temp->name);
printf("%s\n",temp->event);
printf("%f\n",temp->time);
temp = temp->next;
}
}