How to solve this trouble ? Please help me !

Question

Hi everyone ! I'm fresher in c and c++. I'm having a trouble when I add new data into vector / list . I have a method like :
void List(vector<Student> &result)
ifstream list(saveurl, ios::in | ios::binary);
if (list.is_open())
Student st;
while (!list.eof())
if (list.read((char*)&st, sizeof(Student)))
result.push_back(st);
list.close();
First-chance exception at 0x5E84DF58 (msvcp120d.dll) in Student.exe: 0xC0000005: Access violation reading location 0x010FAA4C.
If there is a handler for this exception, the program may be safely continued.
what can I do now ? any suggestions for me ?

Answer 1

On 17/03/2015 20:31, "Tran Hoang Duc" wrote:
as shown below is how is the Student class defined .
struct DateTime
int day,month,year;
class Student
private :
__int64 RollNo;
string StudentName, Course, FatherName,Address,Country;
DateTime DateofBirth;
is it right ?
Perfect, as I suspected :)
Your Student class definition is just fine.
The problem is how you serialize that to/from files.
Since you have non-POD types like std::string as Student data members, you can't just dump your Student internal bytes to disk and read them back to disk.
This won't work, because for example std::string has pointers inside, and the values of those pointers (memory addresses) are meaningless when you write them to file and later load them from file, as just raw bytes, like in this code showed above in
this thread:
Student st;
while(list.read((char*)&st, sizeof(Student)))
 You have to think how to write your Student class to files.
You can use XML, JSON, or even simple comma separated values text files.
Even if you use some custom binary format for your Student instances, you should pay attention to properly write the text stored in your strings to files, and read that back into std::string data members.
 Giovanni