I am trying to print out the results of the linked list in the reverse order that they were entered in. The program takes 3 inputs, Song name, song length (in seconds) and copyright. The program should take the list of songs and print the in the reverse order that they were entered in.
I am not too familiar with linked list. This is my first time using it as sort of a database.
#include <stdio.h>
#include <stdlib.h>
#pragma warning(disable:4996)
//defining struct
typedef struct node
{
char songName[20];
int songLength;
int copyright;
struct node * next;
}node;
//defining prototypes
node *create(int n);
void display(node *head);
int main()
{
int n = 0;
node *head = NULL;
printf("How many entries?\n");
scanf("%d", &n);
//call to create list
head = create(n);
printf("\nThe linked list in order is:\n");
display(head);
return 0;
}
node *create(int n)
{
node *head = NULL;
node *temp = NULL;
node *p = NULL;
for (int i = 0; i < n; i++)
{
temp = (node*)malloc(sizeof(node));
printf("What is the name of song %d\n", i + 1);
//fgets(temp->songName, 20, stdin);
scanf("%s", &temp->songName);
printf("What is the length of song %d (in seconds)?\n", i + 1);
scanf("%d", &temp->songLength);
printf("Is song %d copyrighted?(1 = YES, 0 = NO)\n", i + 1);
scanf("%d", &temp->copyright);
temp->next = NULL;
if (head == NULL)
{
head = temp;
}
else
{
// if not empty, attach new node at the end
p = head;
while (p->next != NULL)
{
p = p->next;
}
p->next = temp;
}
}
return head;
}
void display(node *head)
{
node *p = NULL;
if (head == NULL)
{
printf("List is empty\n");
}
else
{
p = head;
while (p != NULL)
{
printf("Song: %s, ", p->songName);
printf("%d minutes, ", p->songLength);
if (p->copyright == 1)
{
printf("Copyrighted\n");
}
else if (p->copyright == 0)
{
printf("No copyright\n");
}
p = p->next;
}
}
}
So if Input the following:
Song 1 - All Star (song name), 237 (seconds), 0 (no copyrights)
song 2 - Crab Rave, 193, 0
song 3 - 7 rings, 185, 1(copyrights)
The output should be:
7 rings, 185, 1
Crab Rave, 193, 0
All Star, 237, 0
If you have a single (forward) linked list, the probably easiest way to print it in reverse order is using recursion:
void display_recursive(node *n) {
if (!n) {
return;
}
display_recursive(n->next);
printf("Song: %s, ", n->songName);
...
}
Recursion means that a function is calling itself (until some end-condition, the anchor, is reached). By that way, program flow will build up a "stack" of display_recursive- function calls, with the first node, then the second node, ..., until it reaches the last node; by then, recursion stops, and the print part of display_recursive is handled, starting with the last node backwards.
Hope this explanation helps; Try it out in the debugger to see what happens.