Tiny Linked List error in C - c

Question

I have this four files,
tinyll.c tinyll.h in /home/user/lib
test.c tinyll.h in /home/user/code
and compile with this instructions for create a static library
libtinyll.a and use it.
; in lib
$ gcc -c tinyll.c
$ ar -cvq libtinyll.a *.o
; in code
$ gcc -o test test.c ../lib/libtinyll.a
Until here all is ok. But I don't know why I obtain segmentation fault because the lines from [CODE ERROR] but showElements work. The target is not pass code from test.c to tinyll.c for treat the tiny list linked. How fix that?
/////////////////////////////////// test.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "tinyll.h"
int main(int argc, char *argv[])
{
progname = argv[0];
char *file = "fwords";
int n;
PTLL lsone = NULL;
n = loadfileinTLL(file,&lsone);
// work. good.
showElements(lsone);
// [CODE ERROR]
// Why here dont work?
// segmentation fault, load the first word
// but in the second crash.
while (lsone != NULL) {
printf("%s",lsone->word);
lsone = lsone->next;
}
return 0;
}
/////////////////////////////////// tinyll.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "tinyll.h"
void addElement(PPTLL lst, char data[])
{
PTLL elemt;
elemt = (PTLL) malloc(sizeof(TLL));
if (elemt == NULL) {
fprintf(stderr, "%s: insufficient memory.\n", progname);
exit(1);
}
if (*lst == NULL)
{
strncpy(elemt->word, data, 45);
elemt->next = NULL;
*lst = elemt;
}
else {
// add in front of list
strncpy(elemt->word, data, 45);
elemt->next = *lst;
*lst = elemt;
}
}
void showElements(PTLL lst)
{
while (lst != NULL) {
printf("%s\n",lst->word);
lst = lst->next;
}
}
int loadfileinTLL(char *filepath, PPTLL plst)
{
FILE *f;
if ((f = fopen(filepath, "r")) == NULL) {
fprintf(stderr, "%s: error to load file %s.\n", progname, filepath);
exit(1);
}
char buf[45]; int n=0;
while (fgets(buf,sizeof(buf),f) != NULL) {
char *nl;
if ((nl = strchr(buf,'\n')) != NULL) {
*nl = '\0';
}
addElement(plst,buf);
n++;
}
fclose(f);
return n;
}
//////////////////////////////////// tinyll.h
#include <stdio.h>
#include <stdlib.h>
#ifndef _TINYLL_
#define _TINYLL_
struct list {
char word[45];
struct list *next;
};
// Tiny Linked List
typedef struct list TLL;
typedef struct list *PTLL;
typedef struct list **PPTLL;
char *progname;
#endif

Answer 1

the following code:
1) compiles cleanly
2) performs correctly, with out seg faulting.
3) checks and handles errors correctly
4) cleans up after itself, by freeing any allocated memory
5) removed leading underscores from names
as leading underscores has special meaning to the compiler
tinyll.h
#ifndef TINYLL_
#define TINYLL_
struct list
{
char word[45];
struct list *next;
};
// Tiny Linked List
typedef struct list TLL;
typedef struct list *PTLL;
typedef struct list **PPTLL;
extern char *progname;
void addElement(PPTLL lst, char data[]);
void showElements(PTLL lst);
int loadfileinTLL(char *filepath, PPTLL plst);
#endif // TINYLL_
tinyll.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "tinyll.h"
void addElement(PPTLL lst, char data[])
{
PTLL elemt;
elemt = (PTLL) malloc(sizeof(TLL));
if (elemt == NULL) {
fprintf(stderr, "%s: insufficient memory.\n", progname);
exit(1);
}
if (*lst == NULL)
{
strncpy(elemt->word, data, 45);
elemt->next = NULL;
*lst = elemt;
}
else {
// add in front of list
strncpy(elemt->word, data, 45);
elemt->next = *lst;
*lst = elemt;
}
}
void showElements(PTLL lst)
{
while (lst != NULL) {
printf("%s\n",lst->word);
lst = lst->next;
}
}
int loadfileinTLL(char *filepath, PPTLL plst)
{
int n=0;
FILE *f;
if ((f = fopen(filepath, "r")) == NULL)
{
fprintf(stderr, "%s: error to load file %s.\n", progname, filepath);
n = -1;
}
else
{
char buf[45];
while (fgets(buf,sizeof(buf),f) != NULL)
{
char *nl;
if ((nl = strchr(buf,'\n')) != NULL)
{
*nl = '\0';
}
addElement(plst,buf);
n++;
}
fclose(f);
} // endif
return n;
}
test.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "tinyll.h"
char *progname;
int main(int argc, char *argv[])
{
if( 1 == argc )
{
progname = argv[0];
}
else
{
printf( "USAGE: %s\n", argv[0]);
exit( EXIT_FAILURE );
}
// implied else, right number (0) of arguments on command line
char *file = "fwords";
int n;
PTLL lsone = NULL;
PTLL lstwo = NULL;
n = loadfileinTLL(file,&lsone);
if( n > 0 )
{
// work. good.
showElements(lsone);
// [CODE ERROR]
// Why here dont work?
// segmentation fault, load the first word
// but in the second crash.
lstwo = lsone;
while (lstwo)
{
printf("%s",lstwo->word);
lstwo = lstwo->next;
}
} // endif
while( lsone )
{
lstwo = lsone->next;
free(lsone);
lsone = lstwo;
} // end while
return 0;
}
I used the following for a test file:
one
two
three
four
five
six
and the output was:
six
five
four
three
two
one
sixfivefourthreetwoone