You can use standard c functions, such as fopen, fwrite, to save and read file on different platforms. Of cource, you can use other standard functions to operate with a file. The difficulty is the path to save or read a file.

This article modifies the "HelloWorld" example to show you how to save/read file on different platforms.

Now, CCFileUtils::getWriteablePath() returns a writeable path. You can use it to get the writeable path.

1. Run example on different platforms

1.1 Android

• Copy FileOperation.h and FileOperation.cpp into cocos2d-x/HelloWorld.
• Invoke FileOperation::saveFile() and FileOperation::readFile() in HelloWorld::init().
• Modify cocos2d-x/HelloWorld/android/jni/helloworld/Android.mk.
• 
• Rebuild and run

You will see the log in eclipse like:

Also, you can see the file content:

1.2 iOS

• Copy FileOperation.h and FileOperation.mm into cocos2d-x/HelloWorld.
• Invoke FileOperation::saveFile() and FileOperation::readFile() in HelloWorld::init().
• Add FileOperation.h and FileOperation into project file.
• 
• Rebuild and run

You will see the log in eclipse like:

Also, you can see the file content:

Please reference to the apple document:
iOS Aplication Programming Guide - File & the File system
CHN version

1.3 Windows

• Copy FileOperation.h and FileOperation.cpp into cocos2d-x/HelloWorld.
• Invoke FileOperation::saveFile() and FileOperation::readFile() in HelloWorld::init().
• Add FileOperation.h and FileOperation into project file.
• 
• Rebuild and run

You will see the log in eclipse like:

Also, you can see the file content:

2. Summary

This article just gives a guide of how to save/read file on different platforms. It is not the standard method,
just a workable method.