how do I deal with this segmentation error - c

Question

I keep receiving the same message "segmentation fault: 11"
gdb tells me that the break point is just after the main function. in the line where I declare the int j;
i really do not understand how can that possibly break the code.
the input this function reads is made up of simply 1 string followed by 2 numbers like
john 22 43 sam 11 23
all it's supposed to do is simply to store the entire input in "elenco" and then print the strings.
first i created a struct that matches the input.
then i made a function with the purpose of reading the input and store in a variable.
then i made a function whose variables is the output of the function that read the input ( so the input ) and that prints the strings given
can anybody help me identify the problem and solve it?
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct
{
char name[20];
int distance;
int point;
} throw;
throw *read_file(FILE *f, int *j)
{
int i = 0;
int c;
int Dim = 32;
char buf[1000];
throw *list;
list = malloc(Dim *sizeof(*list));
if (list == NULL)
{
(*j) = 0;
return NULL;
}
while (fgets(buf, sizeof(buf), f)!= NULL)
{
sscanf(buf, "%19s %d %d",
list[*j].name,
&list[*j].distance,
&list[*j].point);
*j += 1;
if ( *j >= Dim)
{
Dim = Dim*2;
list = realloc(list, Dim *sizeof(*list));
if (list == NULL)
{
return NULL;
}
}
}
return list;
}
void print_everything(throw *list, int j)
{
int c;
for (c=0; c < j; c++ )
{
printf("%d\n",list[c].distance);
}
}
int main(int argc,const char *argcv[])
{
int j = 0;
FILE *file;
throw *list;
if (!( argc != 3))
{
printf("file's dimension is wrong\n");
return -1;
}
file = fopen(argcv[1], "r");
list = read_file(file, &j);
print_everything(list, j);
fclose(file);
return 0;
}
input1.txt
Mario 20 30
Giorgio 30 40
Mario 40 40
Davide 32 20
Mario 9 32
that is exactly what the file contained

Answer 1

Your program is fine. Your problem is in input1.txt , you need
Mario 20 30
Giorgio 30 40
Mario 40 40
Davide 32 20
Mario 9 32
Each line needs a \n as you read with fgets()

Answer 2

Made some changes on you code you are making the use of the lists wrong try to use pointers
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAXSTR 250
typedef struct elenco
{
char *name;
int distance;
int point;
struct elenco *next;
} throw;
throw *list_add(throw *list, int distance, int point, const char *name)
{
throw *new = malloc(sizeof(throw));
if (new != NULL) {
new->distance = distance;
new->point = point;
new->name =(char*)malloc(strlen(name)+1);
strcpy(new->name,name);
new->next = list;
return new;
}
return list;
}
throw *read_file(FILE *f)
{
char buf[MAXSTR];
throw *list = malloc(sizeof(throw));
while (fgets(buf, sizeof(buf), f)!= NULL)
{
char name[MAXSTR];
int distance;
int point;
sscanf(buf, "%s %d %d",
name,
&distance,
&point);
list = list_add(list, distance, point, name);
}
return list;
}
void print_everything(throw *list)
{
while (list) {
printf("%d\n",list->distance);
list = list->next;
}
}
int main()
{
int argc;
const char *argcv;
FILE *file;
if (!( argc != 3))
{
printf("file's dimension is wrong\n");
return -1;
}
file = fopen(&argcv[1], "r");
throw *list = read_file(file);
print_everything(list);
fclose(file);
return 0;
}