Thread: C in Real Life

After Gustaff's post about higher level languages possibly having better run time, I remembered a thread we had here, that dealt with just that situation.

The thread ran to 5 pages, so I'll pull the highlights together (full thread link):
Python --> C

"Macha" had a problem. His company had hundreds of thousands of tuples that had to be looked at, and those with two or more matching values with any other tuple, needed to be noted, for more analysis.

Macha was familiar with Python, but found the run-time to be VERY long. We asked for, and received from him, a sample file of tuples, that his Python program ran in 4.9 seconds.

Quickly, Salem slaughtered that run time. Perhaps not unexpected, because Salem is a very experienced C programmer. More telling imo, is that two other programmers also did the same thing. My programs run time was 0.05 seconds on his Python data that had a run-time of 4.9 seconds. I'm a hobby C programmer, not a pro.

Later, we created a much larger file, that ran in 3.2 seconds in C. This was the next bit of dialog:

Originally Posted by Adak

How does 3.2 sec's compare with Python's time on the larger file?

Originally Posted by Macha

It's not even worth waiting for it. It's well well beyond hard-boiled-egg-time.

In the end, MK27 and others, also found an algorithm improvement for his Python program. The C program, running in C#, still took 15 seconds, even after this improvement. That's 4.69 times as long as the C run-time.

You'll see this over and over again, if you hang around mixed language programming forums and newsgroups. People finding nice speed-ups to their program, when it's set up to run in C or C++. It's not a coincidence.

I have never heard of a program, that ran slower, after being changed over from an interpreted language, to C. It could happen for the reasons Gustaff stated (poor choice of an algorithm in C), but I've never heard of it, except from inexperienced C/C++ programmers.

C programmers learn more about algorithms, because we do "roll our own". After awhile, we learn to "roll", rather better than you would expect.

I believe you'd be hard pressed to find time-critical programs, that haven't been switched over to run in a compiled language - especially C or C++, as soon as possible.

Adding on what Adak said I think the very fact that the mainstream Python implementation CPython is written in C speaks miles on the performance of C. Python is a nice language and has some very useful features(particularly in terms of list processing) but in terms of actual performance it will always be inferior to C because of 2 simple reasons:

1) C is compiled while Python is interpreted(although there is some work done on Python compilers)
2) C is so low-level that you can almost smell the CPU registers. In fact, you can even choose to store something small on a register rather than on the stack or heap.

On the other hand, Python might have an edge on C in terms of productivity (easier to debug, more readable, more abstraction, etc.). However, sigh, I feel like many people are confused about the difference between these two magic 'P' words: productivity vs performance.

In terms of algorithms, I think Adak said what we all know to be true:

"C programmers learn more about algorithms, because we do "roll our own". After awhile, we learn to "roll", rather better than you would expect. "

Appreciate your input, but Delphi (and Pascal), are compiled, not interpreted, languages:**

What is Delphi?
Borland Delphi is a high-level, compiled, strongly typed language that supports structured and object-oriented design.

Although C is somewhat faster than Delphi in most programs, my "gripe" is with the naive claim that interpreted languages run as fast overall, as C.

Another data point for this is in chess programming, where blazing speed is so frequently the difference between a successful program, or a commercial or personal, embarrassment.

I don't believe the rumors about chess programmers selling their relativess into slavery, in exchange for a bit more speed for their programs.

You get the idea - your program is looking 3 moves ahead, but your opponent's program is looking 4 moves ahead - your chances of winning are decidedly *bleak*.

Speed is crucial to success. The algorithms used are complex - evaluations are based on a myriad of chess themes, based on an incomplete search and preliminary estimates.

So how many of the top 200 chess programs run on an interpreted language? How many use these "superior" libraries, JIT, and any of the host of great features in the interpreted languages?

None

What languages are used? C, and C++, (with portions done in assembly).

Of course.

**CommonTater stated Delphi was a compiled language, but I wanted to emphasize that point. Clumsily worded on my part.