Hello everyone ! I'm going to make a very complicated project and that's why i need your help. As you have seen in the subject , I want to "upload code to arduino via bluetooth using a custom app" . Let me explain why I want to do that.
I want to make a gift for about 5 friends , and this gift will be a house system alarm , witch will have a gprs , a bluetooth module and some temperature and door open sensors. This system it will send an sms when a door opens. But , this SMS should be sent to a specific phone number . For this , I ' ll create an app through they can put his phone number. The app will connect to arduino via bluetooth and it will upload the code with the phone number in it to arduino . I do not want them to use other applications like bulino loader , I want that the transmission to be directly from my app to bluetooth module , and then in to arduino.
Sorry for wrong category. Can anyone help me ??
You don't need to re-upload the whole program to change a phone number. Just change the variable that contains the phone number.
But to be honest, the projects seems wayyy over your head. Even without the custom upload app. All I can say, take baby steps! Split the projects up in to minuscule parts.
I thought about changing only the variable , but every time the battery dies , I need to retype it.
I know it's very complicated , but i have experience and I really want to do this. Thanks !
Any ideas ?
No you don't. (I guess that applies to the battery dying part as well as the experience...)
For the first part, look up EEPROM 
Thanks a lot man ! You just saved my life . Thank you !