How does sbrk() work in C++?

Question

Where can I read about sbrk() in some detail?

How does it exactly work?

In what situations would I want to use sbrk() instead of th

Answer 1

You've tagged this C++ so why would you use 'cumbersome' malloc() rather than new? I am not sure what is cumbersome about malloc in any case; internally maybe so, but why would you care? And if you did care (for reasons of determinism for example), you could allocate a large pool and implement your own allocator for that pool. In C++ of course you can overload the new operator to do that.

sbrk is used to glue the C library to the underlying system's OS memory management. So make OS calls rather than using sbrk(). As to how it works, that is system dependent. If for example you are using the Newlib C library (commonly used on 'bare-metal' embedded systems with the GNU compiler), you have to implement sbrk yourself, so how it works in those circumstances is up to you so long as it achieves its required behaviour of extending the heap or failing.

As you can see from the link, it does not do much and would be extremely cumbersome to use directly - you'd probably end-up wrapping it in all the functionality that malloc and new provide in any case.