Path: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: bart <bc@freeuk.com>
Newsgroups: comp.lang.c
Subject: Re: Suggested method for returning a string from a C program?
Date: Mon, 24 Mar 2025 16:02:57 +0000
Organization: A noiseless patient Spider
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On 24/03/2025 15:00, Muttley@DastardlyHQ.org wrote:
> On Mon, 24 Mar 2025 15:32:32 +0100
> David Brown <david.brown@hesbynett.no> wibbled:
>> On 24/03/2025 15:07, bart wrote:
>>> What was strange was that that one view was shared by pretty much
>>> everyone in comp.lang.c.
>>
>> Do you know what the people in comp.lang.c have in common?
>>
>> We program in C.
>>
>> Do you know /why/ people program in C?
>>
>> There can be many reasons, but a very common one is that they want fast
>> resulting binaries.  Most serious programmers are familiar with more
>> than one language, and pretty much all other languages are higher level,
>> easier, and have higher developer productivity than C - but the
>> resulting binaries are almost always slower.
>>
>> C programmers are typically not bothered about build times because a)
>> their build times are rarely high (Scott's projects are C++), and b),
>> they are willing to sacrifice high build times if it means more
>> efficient run times.
> 
> I'm not sure what kind of build time he's looking for either. On this Mac
> ARM laptop I can compile a 7600 line utility I wrote in C in 0.8 seconds
> real time, and that is using a makefile with 18 seperate source files and
> a header and includes link time. So unless he's rebuilding the linux kernel
> every day I don't see what the problem is.
> 
> loki$ ls *.c *.h | wc -l
>        19
> loki$ wc -l *.c *.h
> :
> :
>       691 globals.h
>      7602 total
> loki$ time make
> :
> :
> real	0m0.815s
> user	0m0.516s
> sys	0m0.252s


So, your throughput is a whopping 9.5K lines/second?

Here's a project I'm working at the minute (not in C):

   c:\bx>tim mm bb
   Compiling bb.m to bb.exe
   Time: 0.066

Build time is 1/15th of a second, for about 30K lines (so 450Klps). But 
I also want to compile this via C, to take advantage of gcc's superior 
optimiser. So first I transpile to C (that's also under 70ms):

   c:\bx>mc -c bb
   Compiling bb.m to bb.c

Now I can invoke gcc:

   c:\bx>tim gcc -O3 -s bb.c -o dd
   Time: 12.316

The generated C file is 38Kloc, and takes 12 seconds. It takes nearly 
TWO HUNDRED TIMES longer to build.

I can tolerate that from time to time,

Using gcc-O0 takes only two seconds, but since it's generating slower 
code than mine, there is no point:

            Build time        Run time

bcc bb       70 ms            628 ms
gcc -O0    2000 ms           1517 ms
gcc -O3   12300 ms            579 ms

(On this test, gcc-O3 was 8% faster, but in depends on the input to this 
interpreter project. On average it is 25% faster.)