I am trying to read from a text file into a linked list of structs in C.
In the program I have a struct definition in a .h
file as such:
typedef struct SystemDetails *SyDetails;
The struct itself is defined in a .cpp file as such:
struct SystemDetails //stores system users data from the list
{
char fname[20],lname[20],password[7],email[30],SQuestion[10],SAnswer[10];
long unsigned int id;
int memory_alloc, request_ind,delete_ind;
SystemDetails *next;
};
The function that deals with the file and the data transfer is:
SyDetails System_Data()
{
FILE *fp=NULL;
SyDetails head=NULL,curr=NULL;
char fname[20],lname[20],password[7],email[30],SQuestion[10],SAnswer[10];
long unsigned int id=0;
int memory_alloc=0,request_ind=0,delete_ind=0;
fp=fopen("SystemList.txt","r+");
if(fp==NULL)//if file doesn't exist on the pc open a new file
{
printf("error,file cant open\n");
exit(-1);
}
else
{
while(fscanf(fp, "%s %s %d %s %s %s %s %d %d %d", &fname,&lname,&id,&email,&password,&SQuestion,&SAnswer,&memory_alloc,&request_ind,&delete_ind)!=EOF)
{
if(head==NULL)
{
head=(SyDetails) malloc(sizeof (SyDetails));
curr=head;
}
else
{
curr->next=(SyDetails) malloc(sizeof (SyDetails));
curr=curr->next;
}
strncpy(curr->fname, fname, 20);
strncpy(curr->lname, lname, 20);
curr->id=id;
strncpy(curr->email, email, 30);
strncpy(curr->password, password, 10);
strncpy(curr->SQuestion, SQuestion, 10);
strncpy(curr->SAnswer, SAnswer, 10);
curr->memory_alloc=memory_alloc;
curr->request_ind=request_ind;
curr->delete_ind=delete_ind;
curr->next=NULL;
}
}
return head;
}
Anyway the text file has 3 records , the first row works when head==NULL
but at the second time when the function gets to the else
to malloc
the next node of the linked list it crashes at the malloc
line and I get an error that says:
"Windows has triggered a breakpoint in final-project.exe.
This may be due to a corruption of the heap, which indicates a bug in final-project.exe
or any of the DLLs it has loaded.
This may also be due to the user pressing F12
while final-project.exe
has focus.
The output window may have more diagnostic information."
My guess is that there is something with the way I defined the pointers in the function.
I would appriciate any help , thanks!