Incorrect entry in file from linked list - c

Question

This is the one of main part of the code that the pls format file should convert to m3u format song under numbers of seconds which specified :
[playlist]
NumberOfEntries=3
File1=C:\muzika\Chris Rea - Looking For The Summer.mp3
Title1=Chris Rea - Looking For The Summer
Length1=302
File2=C:\muzika\Simply Red - Holding Back The Years.mp3
Title2=Simply Red - Holding Back The Years
Length2=265
File3=C:\muzika\Mambo Kings - Luz de luna.mp3
Title3=Mambo Kings - Luz de luna
Length3=207
Version=2
convert to:
#EXTINF:207,Mambo Kings - Luz de luna
C:\muzika\Mambo Kings - Luz de luna.mp3
#EXTINF:265,Simply Red - Holding Back The Years
C:\muzika\Simply Red - Holding Back The Years.mp3
.
if ( file != NULL )
{
char line[256];
while (fgets(line, sizeof line, file) != NULL)
{
if (count == lineNumber)
{
int j=0;
if (line[0] == 'F') {
int brojac=6;
while(line[brojac]!='\n'){
ffolder[j]=line[brojac];
j++;
brojac++;
}
folder=ffolder;
}
if (line[0] == 'T') {
int brojac=7;
while(line[brojac]!='\n'){
naslov1[j]=line[brojac];
j++;
brojac++;
}
naslov=naslov1;
}
if (line[0] == 'L') {
int brojac=8;
while(line[brojac]!='\n'){
vremee[j]=line[brojac];
j++;
brojac++;
}
vreme=vremee;
//intvreme = folder11(line);
if(atoi(vremee)<atoi(argv[3])) {
//fprintf(out, "\n#EXTINF:%s,%s\n%s", vremee,naslov1,ffolder);**key part**
struct pesma *link = (struct pesma *) malloc(sizeof(struct pesma));
link->folder = folder;
printf("%s\n",folder);
link->naslov = naslov;
printf("%s\n",naslov);
link->vreme = atoi(vreme);
link->next = NULL;
if (!glava) {
glava = link;
} else {
struct pesma *tail = glava;
while (tail->next) {
tail = tail->next;
}
tail->next = link;
}
}
}
}
else
{
count++;
}
}
}
When I call the function that should print the elements of the linked list, for each song that meets the criteria, print this:
#EXTINF:207,Mambo Kings - Luz de luna
C:\muzika\Mambo Kings - Luz de luna.mp3
#EXTINF:265,Mambo Kings - Luz de luna
C:\muzika\Mambo Kings - Luz de luna.mp3
vreme is normal,but folder and naslov are from last last line in file.
However, if I use the fprintf function (in the key part in the main code) instead of a concatenated list, the printout is correct, but then I can't sort alphabetically.
fprintf(out, "\n#EXTINF:%s,%s\n%s", vremee,naslov1,ffolder);
I'm wondering why the linked list is printed like this?

Answer 1

my guess - cant do better since we have an incomplete program
link->folder = folder;
link is a char * member. If so you should do
link->folder = strdup(folder);
otherwise they all end up pointing to the buffer 'folder' and whatever it last contained

Answer 2

Your application modified so that it reads the input data into a linked list. Using char arrays in the song struct makes them easier to handle. For sorting the list insertion sort is used.
There remains some work to do with this code:
Extract duplicate code into functions
Complete error handling, a.o. check all function return values
Maybe use a command line argument for the input file name
In general, try to use English words for names (data structures, functions, variables, etc.).
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX_LINE_LENGTH 256
typedef struct song { // pesma
char file[MAX_LINE_LENGTH];
char title[MAX_LINE_LENGTH]; // naslov
int time; // vreme
struct song * next;
} SONG;
// Insertion Sort
SONG * sort_songs(SONG * root) {
if (root == NULL || root->next == NULL) {
// All lists with less than two elements are already sorted.
return root;
}
// put first element into sorted list
SONG * sorted_root = root;
// start iteration with second element
SONG * iterator = root->next;
// set end of sorted list
sorted_root->next = NULL;
while (iterator != NULL) {
// trace position directly before insertion point
SONG * previous = NULL;
// iterate over already sorted list
SONG * sorted_iterator = sorted_root;
// determine insertion point in already sorted list
while (
// list end not reached
sorted_iterator != NULL
&&
// need to advance in sorted list for proper position
strcmp(sorted_iterator->title, iterator->title) <= 0) {
previous = sorted_iterator;
sorted_iterator = sorted_iterator->next;
}
if (previous == NULL) {
// prepend sorted list with element
SONG * tmp = sorted_root;
sorted_root = iterator;
iterator = iterator->next;
sorted_root->next = tmp;
} else if (sorted_iterator == NULL) {
// append new last element in sorted list
previous->next = iterator;
SONG * tmp = iterator->next;
iterator->next = NULL;
iterator = tmp;
} else {
// insert element at correct position
SONG * tmp = iterator->next;
previous->next = iterator;
iterator->next = sorted_iterator;
iterator = tmp;
}
}
return sorted_root;
}
int main()
{
char line[MAX_LINE_LENGTH];
char *filename = "playlist.txt";
// pointer to first element of the linked song list
SONG *root = NULL; // glava
FILE *file = fopen(filename, "r");
if (file == NULL) {
fprintf(stderr, "Could not open file '%s'!\n", filename);
return EXIT_FAILURE;
}
// read line containing "[playlist]"
fgets(line, sizeof line, file);
// read line containing "NumberOfEntries=3"
fgets(line, sizeof line, file);
char *start_position = strchr(line, '=') + 1;
int number_of_entries = atoi(start_position);
printf("Number of entries: %d\n", number_of_entries);
for (int i = 0; i < number_of_entries; i++) {
// allocate new node for linked list and put it to the front of the list
SONG *node = malloc(sizeof(SONG));
node->next = root;
root = node;
// read file name
if (fgets(line, sizeof line, file) == NULL) {
fprintf(stderr, "Unexpected end of file!\n");
fclose(file);
// TODO: release allocated memory
return EXIT_FAILURE;
}
start_position = strchr(line, '=') + 1;
strcpy(node->file, start_position);
node->file[strlen(start_position) - 1] = '\0';
// read title
if (fgets(line, sizeof line, file) == NULL) {
fprintf(stderr, "Unexpected end of file!\n");
fclose(file);
// TODO: release allocated memory
return EXIT_FAILURE;
}
start_position = strchr(line, '=') + 1;
strcpy(node->title, start_position);
node->title[strlen(start_position) - 1] = '\0';
// read time
if (fgets(line, sizeof line, file) == NULL) {
fprintf(stderr, "Unexpected end of file!\n");
fclose(file);
// TODO: release allocated memory
return EXIT_FAILURE;
}
start_position = strchr(line, '=') + 1;
int time = atoi(start_position);
node->time = time;
}
// read version
if (fgets(line, sizeof line, file) == NULL) {
fprintf(stderr, "Unexpected end of file!\n");
fclose(file);
// TODO: release allocated memory
return EXIT_FAILURE;
}
start_position = strchr(line, '=') + 1;
int version = atoi(start_position);
printf("Version: %d\n", version);
root = sort_songs(root);
SONG * iterator = root;
while (iterator != NULL) {
fprintf(stdout, "\n#EXTINF:%d,%s\n%s", iterator->time, iterator->title, iterator->file);
iterator = iterator->next;
}
fprintf(stdout, "\n");
// free the allocated memory
while (root != NULL) {
SONG * next = root->next;
free(root);
root = next;
}
fclose(file);
return EXIT_SUCCESS;
}
$ gcc -Wall convert_playlist.c
$ ./a.out
Number of entries: 3
Version: 2
#EXTINF:302,Chris Rea - Looking For The Summer
C:\muzika\Chris Rea - Looking For The Summer.mp3
#EXTINF:207,Mambo Kings - Luz de luna
C:\muzika\Mambo Kings - Luz de luna.mp3
#EXTINF:265,Simply Red - Holding Back The Years
C:\muzika\Simply Red - Holding Back The Years.mp3
$