Segfault error when mallocing an array of structs - arrays

Question

after a long time spent trying to debug this I've come for your help.
Basically in this exercise I'm trying to read the string "31|Name1;23|Name2;15|Name3" and store it in an array of struct s_perso where the | are marking the end of an age and the beginning of a name, and where the ; are marking the beginning of a new struct.
Here's the given ft_perso.h :
#include <string.h>
#ifndef FT__PERSO__H
#define FT__PERSO__H
typedef struct s_perso
{
char *name;
float life;
int age;
char *profession;
}
t_perso;
#endif
We will only use the datas age and name from this struct s_perso.
Here's my code :
#include "ft_perso.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
int numberofstructs(char *str)
{
int i;
int length;
i = 0;
length = 0;
if (str[0])
length = 0;
else
{
while (str[i])
{
if (str[i] == ';')
length += 1;
i++;
}
}
return (length);
}
int get_data_length(char *str, int i)
{
int length;
length = 0;
while (str[i] != '|' && str[i] != ';' && str[i] != '\0')
{
length++;
i++;
}
return (length);
}
char *get_data(char *str, int i)
{
int j;
char *str2;
j = 0;
str2 = (char *)malloc(sizeof(char) * get_data_length(str, i) + 1);
while (str[i] != '|' && str[i] != ';' && str[i] != '\0')
{
str2[j] = str[i];
i++;
j++;
}
str2[j] = '\0';
return (str2);
}
t_perso **ft_decrypt(char *str)
{
int i;
int j;
t_perso **textttt_perso;
i = 0;
j = 0;
textttt_perso = (t_perso **)malloc(sizeof(t_perso **));
*textttt_perso = (t_perso *)malloc(sizeof(t_perso *) * numberofstructs(str));
while (j <= strlen(str) && str[j])
{
if (str[j] == ';')
{
i++;
j++;
}
textttt_perso[i]->age = atoi(get_data(str, j));
j = j + get_data_length(str, j) + 1;
textttt_perso[i]->name = get_data(str, j);
j = j + get_data_length(str, j);
}
textttt_perso[i+1] = 0;
return (textttt_perso);
}
int main(void)
{
int i;
t_perso **tab;
i = 0;
char str[29] = "31|Name1;23|Name2;15|Name3";
tab = ft_decrypt(str);
while(i <= numberofstructs(str))
{
printf("age = %d\n", tab[i]->age);
printf("age = %s\n", tab[i]->.name);
i++;
}
}
From my debugging, I get the segfault error on the second call (when i = 1 and we are working on the substring 23) instruction of t_perso **ft_decrypt(char *str) :
textttt_perso[i]->age = atoi(get_data(str, j));
My guess is that my allocation of memory either for the array of struct in itself or the number of arrays it can contain is wrong. I can't point my finger on the problem tho...
Thanks in advance for your help, have a nice day !

Answer 1

You never allocate space for an actual structure. In your example:
textttt_perso = (t_perso **)malloc(sizeof(t_perso **));
allocates space for one pointer and:
*textttt_perso = (t_perso *)malloc(sizeof(t_perso *) * numberofstructs(str));
allocates enough space for 3 pointers. At some point you need to allocate space for the actual structures.
You also have other issues. In numberofstructs() you have if(str[0]) that will cause length to always be zero. Also in numberofstructs(), you count the semi-colons. If there is data after the last sem-colon you would need to add 1 to length.
You have many other issues in this code that will show up if the data isn't perfect but here is an implementation of ft_decrypt that should work. Initial malloc should be to hold the array of pointers. Then the loop should allocate a structure for each array entry.
t_perso** ft_decrypt(char* str)
{
int i = 0;
int j = 0;
t_perso** textttt_perso;
textttt_perso = malloc(sizeof(*textttt_perso) * numberofstructs(str));
while (j <= strlen(str) && str[j])
{
if (str[j] == ';')
{
i++;
j++;
}
textttt_perso[i] = malloc(sizeof(*textttt_perso[i]));
textttt_perso[i]->age = atoi(get_data(str, j));
j = j + get_data_length(str, j) + 1;
textttt_perso[i]->name = get_data(str, j);
j = j + get_data_length(str, j);
}
return (textttt_perso);
}