[英]Segfault error when mallocing an array of structs
after a long time spent trying to debug this I've come for your help.经过很长时间试图调试这个我来寻求你的帮助。 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 |
基本上在这个练习中,我试图读取字符串
"31|Name1;23|Name2;15|Name3"
并将其存储在struct s_perso
的数组中,其中|
are marking the end of an age and the beginning of a name, and where the ;
标志着一个时代的结束和一个名字的开始,以及在哪里
;
are marking the beginning of a new struct.正在标记一个新结构的开始。
Here's the given ft_perso.h:这是给定的 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
.我们将仅使用此结构
s_perso
中的数据age
和name
。
Here's my code:这是我的代码:
#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)
:从我的调试中,我在第二次调用(当
i = 1
并且我们正在处理 substring 23
时)得到t_perso **ft_decrypt(char *str)
指令的段错误:
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.我的猜测是,我为结构本身的数组或它可以包含的 arrays 的数量分配 memory 是错误的。 I can't point my finger on the problem tho...
我不能把我的手指指向这个问题...
Thanks in advance for your help, have a nice day !提前感谢您的帮助,祝您有美好的一天!
You never allocate space for an actual structure.您永远不会为实际结构分配空间。 In your example:
在您的示例中:
textttt_perso = (t_perso **)malloc(sizeof(t_perso **));
allocates space for one pointer and:为一个指针分配空间并且:
*textttt_perso = (t_perso *)malloc(sizeof(t_perso *) * numberofstructs(str));
allocates enough space for 3 pointers.为 3 个指针分配足够的空间。 At some point you need to allocate space for the actual structures.
在某些时候,您需要为实际结构分配空间。
You also have other issues.你还有其他问题。 In
numberofstructs()
you have if(str[0])
that will cause length
to always be zero.在
numberofstructs()
你有if(str[0])
这将导致length
始终为零。 Also in numberofstructs()
, you count the semi-colons.同样在
numberofstructs()
中,您计算分号。 If there is data after the last sem-colon you would need to add 1 to length
.如果最后一个分号后有数据,则需要将 1 添加到
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.如果数据不完美,这段代码中还会出现许多其他问题,但这里有一个应该可以工作的
ft_decrypt
实现。 Initial malloc should be to hold the array of pointers.初始 malloc 应该是保存指针数组。 Then the loop should allocate a structure for each array entry.
然后循环应该为每个数组条目分配一个结构。
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);
}
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