My own application malfunctioning C++ - c++

Question

I can not get my c++ application to work properly, i will paste my simple memory class and a test app here.
Right now i get an access violation and no output when i run it in the console. I use Visual Studio 2015.
I seem to haave problems with my car class, not sure what could be wrong. And i ge some error message if i try to debug. I have no idea how to fix it...
#define WIN32_LEAN_AND_MEAN
enum memtype {typechar = 1, typeint};
class Mem
{
public:
Mem(int size);
void * alloc(memtype t);
void * ptr();
void release();
~Mem();
private:
int sizebytes;
void * p;
};
#include <new.h>
#include "Mem.h"
Mem::Mem(int size)
{
sizebytes = size;
}
void * Mem::alloc(memtype t)
{
if (t==typechar)
{
p = (char *)new char(sizebytes);
return p;
}
}
void * Mem::ptr()
{
return p;
}
void Mem::release()
{
if(p)
delete p;
}
Mem::~Mem()
{
if(p)
delete p;
}
#include "Mem.h"
#include <stdio.h>
int check(void * p)
{
int retval = 0;
if (p == NULL)
{
printf("Memory Fail: NULL pointer...\n");
retval = 0;
}
else
retval = 1;
return retval;
}
class Car
{
public:
Car::Car()
{
Car::name = 0;
Car::brand = 0;
Car::type = 0;
}
int Car::alloc(char *inname, char *inbrand, char *intype)
{
Car::name = new Mem(sizeof(*inname));
if (!check(Car::name->alloc(typechar)))
return 0;
printf("%s", sizeof(*inname));
Car::brand = new Mem(sizeof(*inbrand));
if (!check(Car::brand->alloc(typechar)))
return 0;
printf("%s", sizeof(*inbrand));
Car::type = new Mem(sizeof(*intype));
if (!check(Car::type->alloc(typechar)))
return 0;
printf("%s", sizeof(*intype));
/*sprintf?*/
sprintf_s((char *)Car::name->ptr(), sizeof(*inname), "%s", inname);
sprintf_s((char *)Car::brand->ptr(), sizeof(*inbrand), "%s", inbrand);
sprintf_s((char *)Car::type->ptr(), sizeof(*intype), "%s", intype);
return 1;
}
char * Car::getName()
{
if(Car::name!=0)
return (char *)Car::name->ptr();
}
char * Car::getBrand()
{
if(Car::brand!=0)
return (char *)Car::brand->ptr();
}
char * Car::getType()
{
if(Car::type!=0)
return (char *)Car::type->ptr();
}
Car::~Car()
{
if (Car::name != 0)
delete Car::name;
if (Car::brand != 0)
delete Car::brand;
if (Car::type != 0)
delete Car::type;
}
private:
Mem *name, *brand, *type;
};
void store()
{
}
int main()
{
Mem cartype1(sizeof("Sedan"));
cartype1.alloc(typechar);
check(cartype1.ptr());
Mem cartype2(sizeof("Van"));
cartype2.alloc(typechar);
check(cartype2.ptr());
Mem cartype3(sizeof("Pickup"));
cartype3.alloc(typechar);
check(cartype3.ptr());
sprintf((char *)cartype1.ptr(), "%s", "Sedan");
sprintf((char *)cartype2.ptr(), "%s", "Van");
sprintf((char *)cartype3.ptr(), "%s", "Pickup");
Mem carname(sizeof("Supah Car"));
carname.alloc(typechar);
check(carname.ptr());
Mem carbrand(sizeof("Supah"));
carbrand.alloc(typechar);
check(carbrand.ptr());
sprintf((char *)carname.ptr(), "%s", "Supah Car");
sprintf((char *)carbrand.ptr(), "%s", "Supah");
Car test;
test.alloc((char *)carname.ptr(), (char *)carbrand.ptr(), (char *)cartype1.ptr());
printf("%s is of brand %s and type %s\n", test.getName(), test.getBrand(), test.getType());
char * nullptrtest = NULL;
printf_s("%d", &test);
printf_s("sizeof int %d\n", sizeof(int));
printf_s("Test %s\n", carname.ptr());
return 1;
}

Answer 1

int Car::alloc(char *inname, char *inbrand, char *intype)
{
Car::name = new Mem(sizeof(*inname));
sizeof *inname will give you sizeof(char) == 1
So your name member has allocated array of 1 char exactly.
You later write to this array a lot more. As a result your heap is corrupted.
I do not know why you want to play with emulating memory allocation instead of using std::string - but you need to allocate at least strlen(inname)+1 bytes to store inname