[TUHS] why the leading under score added to function names?

[Steve Nickolas]

On Sat, 25 Feb 2012, Random832 wrote:

> On 2/22/2012 11:30 PM, Greg 'groggy' Lehey wrote:
>> On Thursday, 23 February 2012 at  8:22:17 +1100, Dave Horsfall wrote:
>>> On Wed, 22 Feb 2012, arnold at skeeve.com wrote:
>>>> It also shows the consequences a small, apparently local decision
>>>> can have: here we are 40+ years later and GCC on Windows is still
>>>> preprending underscores to function names!
>>> When it comes to Windoze, nothing surprises me any more.  Unix has
>>> evolved over the years, but Windoze was spat out and hatched.
>> I'm no friend of Microsoft either, but gcc isn't exactly Microsoft.
>> What Arnold mentions here is Unix history in action.
>> 
> Yes and no. IIRC, gcc doesn't do that on, for example, Linux ELF. it's done 
> on windows, I assume, in deference to the windows 32-bit ABI for cdecl 
> calling convention functions.
>
> Now, as far as where windows gets that from (just because something evolved 
> within one company doesn't mean it didn't evolve), supposedly early versions 
> of Microsoft C (pre-ANSI) were very conservative in terms of adhering to the 
> "standard" set by Unix C and K&R - this could have extended to the prepending 
> of underscores. For instance, this is, according to Raymond Chen, why they 
> added WinMain rather than extending main (they didn't know if extensions to 
> main would be allowed). I would also guess it's why MSVC stdio is implemented 
> on top of an imitation of Unix system calls which is in turn implemented on 
> top of DOS/windows; and why MSVC time_t is defined as seconds since 1970. 
> There are comments in the code referring to XENIX in various places relating 
> to I/O and timestamps, so it's possible that MSVC's C library was indeed, to 
> some small degree, based on Unix.

Though DOS's file i/o calls, starting in 2.0, were much the same as 
Unix's already.  Its open, close, read, write have the same basic 
semantics and at one point it was possible to have DOS require a syntax 
like \dev\con for devices.

-uso.