C program execution: Does it run in a process or a thread?

Question

I run a sample hello world program in C using Code Blocks.

When it executes it says the process returned 0 .

I know that it is run by the Operating system.

I want to know a few things:

1. Is the program I executed associated with a separate process or the OS allocates a separate thread to it?

2. When a function is called in Windows 32 bit or 64 bit, is the code segment register also pushed to stack?

Answer 1

The answer to your question depends upon how you view a process.

IN the traditional process model where a process is a schedulable entity with an address space, you'd say that your program executed a process.

If you want to look at this traditional model as a process having a single thread, then your program ran in on thread.

It's just a word game.

If you're running on a system that schedules threads natively, then your program existed in a process that contained a thread where the execution took place.

There are no segments in 64-bit.