Question

I am really struggling to see why the following code will not work and causes a segfault.

Car *newCar;
Car *oldCar;
newCar->engineSize = 1500;
memcpy(newCar, oldCar, sizeof(Car)); 

I am obviously missing something very fundamental here but don’t know what it is. Any help would be greatly appreciated.

Thanks

Answer 1

You need to allocate memory for it.

Car* newCar = malloc(sizeof(Car));
Car* oldCar = malloc(sizeof(Car));
...
free(oldCar);
free(newCar);

If you don’t need to use the pointer elsewhere, you could use stack-allocation.

Car newCar;
Car oldCar;
newCar.engineSize = 1500;
memcpy(&newCar, &oldCar, sizeof(newCar));