segmentation fault when accesing into a structure - c

Question

When I am executing printf command for level->description, the program gives me segmentation fault. I don't know why. Should I use malloc to repair it? The content (only 1 line ending with '\n') of file sokoban.dat is "chicago;addie;story begins here;-----#####-----------|-----##$.#-----------|-----#####-----------"
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
typedef struct {
char *name;
char *description;
char *password;
char *map;
struct level *next;
//char *solution;
} LEVEL;
LEVEL* parse_level(char *line) { //parsing from file into the structure
LEVEL level;
char level_name[50];
char level_password[50];
char level_description[100];
char level_map[200];
int i = 0;
int j = 0;
while (line[i] != ';') { //getting level name
level_name[j] = line[i];
i++;
j++;
}
level_name[j]='\0';
level.name=&level_name[0];
//strcpy(&level.name,level_name);
//printf("%s\n",level.name);
printf("%s\n",level_name);
j = 0;
i++;
while (line[i] != ';') { //getting level password
level_password[j] = line[i];
i++;
j++;
}
level_password[j]='\0';
level.password=&level_password[0];
printf("%s\n",level_password);
j = 0;
i++;
while (line[i] != ';') { //getting level description
level_description[j] = line[i];
i++;
j++;
}
level_description[j]='\0';
level.description=&level_description[0];
printf("%s\n",level_description);
j = 0;
i++;
while (line[i] != '\n') { //getting level map
level_map[j] = line[i];
i++;
j++;
}
level_map[j]='\0';
level.map=&level_map[0];
printf("%s\n",level_map);
j = 0;
level.next=NULL;
LEVEL* levelPointer=&level;
return levelPointer;
}
int main(){
FILE *fp = fopen("sokoban.dat", "r");
if( fp == NULL ){
printf("No such file\n");
return 1;
}
char line[500];
//strcpy(line,"");
char c;
int i=0;
while((c = fgetc(fp)) != '\n'){ //reading from file 1 by 1 character
line[i]=c;
i++;
}
printf("%s\n",line);
LEVEL* level;
level=parse_level(line);
//printf("%s\n",level->description); **//!!! this is where error occur**
printf("%s\n",level->map);
return 0;
}

Answer 1

In the function, parse_level() you take addresses of all the local variables and copy into the struct variable level and return level. All these copy of local addresses and using those objects later after their lifetime make your program illegal and causes undefined behaviour.
You should read about basics of language first and understand concepts such as pointers, arrays, returning values from a function, returning pointers etc before diving deeper.
The ones related to your problems are:
returning a local variable from function in C
Since I can't return a local variable, what's the best way to return a string from a C or C++ function?
Undefined, unspecified and implementation-defined behavior
Undefined behavior and sequence points
The Definitive C Book Guide and List

Answer 2

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct level {
char *name;
char *description;
char *password;
char *map;
struct level *next;
//char *solution;
} LEVEL;
#if 0
char *strdup(const char *str){
size_t len = strlen(str);
char *ret = malloc(len + 1);
if(ret){
memcpy(ret, str, len + 1);
//ret[len] = '\0';
}
return ret;
}
#endif
LEVEL* parse_level(char *line) {
//Returns the allocated memory
LEVEL *level = malloc(sizeof(LEVEL));
char *token;
token=strtok(line, ";");//It cut the string as a separator the ';'.
level->name = strdup(token);//Copy the memory allocated strings cut out.
token=strtok(NULL, ";");//Get next token
level->password = strdup(token);
token=strtok(NULL, ";");
level->description = strdup(token);
token=strtok(NULL, ";");
level->map = strdup(token);
level->next = NULL;
#if DEBUG
printf("debug print : level\n");
printf("%s\n", level->name);
printf("%s\n", level->password);
printf("%s\n", level->description);
printf("%s\n", level->map);
#endif
return level;
}
void LEVEL_free(LEVEL *p){
free(p->name);
free(p->password);
free(p->description);
free(p->map);
free(p);
}
int main(){
FILE *fp = fopen("sokoban.dat", "r");
if( fp == NULL ){
printf("No such file\n");
return 1;
}
char line[500];
char c;
int i=0;
while((c = fgetc(fp)) != '\n'){ //reading from file 1 by 1 character
line[i]=c;
i++;
}
line[i] = '\0';
printf("%s\n",line);
LEVEL* level;
level=parse_level(line);
printf("%s\n",level->description);
printf("%s\n",level->map);
LEVEL_free(level);//free for malloced memory
return 0;
}