How do I create a save file for a C++ game?

You need use serialization to save your variables in memory to your hard drive. There are many types of serialization, in .NET XML is a common format, though there are binary and JSON serializers available. I'm not much of a C++ programmer, but a quick search turned up a few examples on serialization in C++:

• http://www.functionx.com/cpp/articles/serialization.htm
• http://www.osix.net/modules/article/?id=348
• http://chuchusoft.com/serialization/index.html

The variables you will be interested in are going to probably be related to game state. For example, you will probably want to know this type of information

1. The player was playing level 3
2. The player was at X, Y world coordinates
3. The player has three items in his backpack
   1. Weapon
   2. Armor
   3. Food

You wont really care what textures are being used (unless your player can change their appearance, that's a special case), because they are usually the same. You need to focus on saving important gamestate data.

When you start your game, you start as normal for a "new" game (this loads your textures, models, etc) but at appropriate time you load the values from your save file back into the game state object replacing the "default" new game state. Then you allow the player to resume playing.

I've greatly simplified it here, but you should get the general idea. If you have a more specific question ask a new question here and we can try to help you with it.

Typically this is specific to your game. I'm sure you've learned about writing to and reading from files in your classes so far. The basic idea is:

1. When exiting the game, write the values you want to save to a file.
2. When loading the game, check to see if a save file exists, if it does, load the read the values in to your program. If the file does not exist, continue like you do now and set the values to their starting/default values.

What you write is up to you, it depends on your game. One way of writing is to write out the variables you want in a specific order as a byte stream. Then when loading, read them in to your program in the same order.

For example (in quick pseudo code):

SaveGame(FileInput file) {
    file.writeInt(playerLevel);
    file.writeInt(playerHealth);
    file.writeInt(gameProgress);
}

LoadGame(FileInput file) {
    if(file.exists()) {
        playerLevel= file.readInt();
        playerHealth = file.readInt();
        gameProgress = file.readInt();
    } else {
        playerLevel = 1;
        playerHealth = 100;
        gameProgress = 0;
    }
}

There are probably a large number of ways to do this, but the simplest that I always found and have used both personally and professionally is to make a structure that contains all of the values I want saved.

struct SaveGameData
{
    int              characterLevel; // Any straight up values from the player
    int              inventoryCount; // Number of items the player has on them or stored or what not
    int[STAT_COUNT]  statistics;     // This is usually a constant size (I am tracking X number of stats)
    // etc
}

struct Item
{
    int itemTypeId;
    int Durability; // also used as a 'uses' count for potions and the like
    int strength;   // damage of a weapon, protection of armor, effectiveness of a potion
    // etc
}

I then just fwrite/fread the data to and from a file using the basic File IO values. The inventoryCount is the number of Item structures that are saved after the main SaveGameData structure in the file so I know how many of those to read after fetching that data. The key here is that when I want to save something new, unless its a list of items or the like, all I have ever have to do is add a value to the structure some where. If its a list of items then I will have to add a read pass like I have already implied for the Item objects, a counter in the main header and then the entries.

This does have the downside of making different versions of a save file incompatible with each other with out special handling (even if it is just default values for each entry in the main structure). But overall this makes the system easy to extend just by adding in a new data value and putting a value into it when needed.

Again, quite a few ways to do this and this might lead more towards C than C++, but it has gotten the job done!

First you need to decide what data needs to be saved. For instance, this could be the location of the character, his score, and the number of coins. Of course, your game will likely be much more complex, and so you will need to save additional data such as the level number and enemy list.

Next, write code to save this to a file (use ofstream). A relatively simple format you can use is as follows:

x y score coins

And so the file would look like:

14 96 4200 100

Which would mean he was at position (14, 96) with a score of 4200 and 100 coins.

You also need to write code to load this file (use ifstream).

Saving enemies can be done by including their position in the file. We can use this format:

number_of_enemies x1 y1 x2 y2 ...

First the number_of_enemies is read and then each position is read with a simple loop.

One addition/suggestion would to add a level of encryption to your serialization so users cannot text edit their values to "9999999999999999999". One good reason to do this would be to prevent integer overflows (for example).

I think your best bet is boost::serialization because is easy to propagate down in your hierarchy. You only need to call the top object's save/load function and all your classes are easily created.

See: http://www.boost.org/doc/libs/1_49_0/libs/serialization/doc/index.html