Summary: in this tutorial, you will learn about C variables that allow you to manipulate data in your program. A variable is a meaningful name of data storage location in computer memory. When using a variable, you refer to a memory address of computer.
Overheating of the CPU caused by a temperature problem is definitely a bad sign as it can destroy the processor and can cause instabilities in the hardware of the system. This can lead to it rebooting as well.
It has a temperature sensor which it uses to detect overheat. The phone will cease operation until the device cools down. The sensor is not otherwise available to applications.