Using File IO to Save and Load Games - Learn C++ for Game Development - page 240

for (auto& serializable : m_serializables)
{
Serializable* pSerializable = serializable.second;
file << pSerializable->GetId();
file << std::endl;
pSerializable->OnSave(file);
file << std::endl;
file << std::endl;
}
}
An ofstream object is initialized by passing it the file name you wish to write to. You can then use the
standard << operator to write data to the file. The o in ofstream stands for output, the f for file, and
stream for its ability to stream data, meaning we are working with an output file stream .
The Save method begins by writing out a true . This bool is used to determine if the save game has
a reinstatable save game inside. We write out false later when the player has completed the game.
Save then loops over all of the stored Serializable objects, writes out their unique ID, and calls the
OnSave method. The std::endl is being written out just to make the text file a little more readable
and easier to debug.
The opposite action to Save is Load , shown in Listing 24-4.
Listing 24-4. The SerializationManager::Load Method
bool SerializationManager::Load()
{
std::ifstream file{ m_filename };
bool found = file.is_open();
if (found)
{
bool isValid;
file >> isValid;
if (isValid)
{
std::cout <<
"Save game found, would you like to load? (Type yes to load)"
<< std::endl << std::endl;
std::string shouldLoad;
std::cin >> shouldLoad;
if (shouldLoad == "yes")
{
while (!file.eof())
{
unsigned int serializableId{ 0 };
file >> serializableId;
auto iter = m_serializables.find(serializableId);