C/C++ Programing

Heh, I here ya, pointers are one of my best friends... but for those who have trouble with the concept they can be a nightmare. C's ambigious nature is part of it's power. You can do virtually anything. There is very little holding you back in the way of rules. That and the compilers produce some of the fastest damn machine code you will ever find. In a way I think of C vs. Java or Pascal like Linux vs. Windows. C allows you to get down to levels that Pascal (at least in the forms I have used it...again, I have never done Delphi) and Java don't allow so it takes longer sometimes to master but you have more control once you do.

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My computer said "WindowsME/2000 or better" so I installed Linux.

One negative thing with pointers is that they will limit the compilers ability to optimize the code, since in many cases the compiler cannot know where a certain pointer points and cannot reuse data already in the register but must rather have to go to the memory instead.
Pointers should be avoided as long as they are not needed. Pointers can also be used in ways that make the code hard to read. Especially the ability to use the ++ or -- operators on pointers in C/C++ is IMO plainly stupid. Using arraystyle indexing (like myPointer[i]) instead makes the code much easier to read and generates in many cases faster code.

I have to disagree with you on the ++, and -- usage on pointers. Imagine you wanted to read in 800 seperate scanf's from the keyboard. Easiest way to do this would be to create a big-*** array, and use pointer's in a for loop to increment the location in the array. Like this:

int x, *ptr, array[800];
for(x = 0, ptr = &array[0]; x < 800; x++, ptr++)
scanf("%d", ptr);

Little crap like that make the increment and decrement operators useful with pointers. But you're right, makes for some amazingly cryptic code as it gets more complicated https://www.sharkyforums.com/images/.../2005/06/4.gif

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Originally posted by jtshaw:
That and the compilers produce some of the fastest damn machine code you will ever find.

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This isn't necessarily so.

Jake's Code Efficency Challenge: http://home.xnet.com/~johnjac/JCEC.htm

Conclusion: A multipass highly optimized compiler is beaten senseless by a single pass compiler which compiles 30-50 times faster (and ends up with as good as or better machine code).

Don't judge a book by it's cover. Just because a compiler is fast, doesn't equate to poorly optimized machine code.

I'd still welcome some pointers (pun) as to what exactly it is that you feel you can do with C that is difficult with other languages. Pascal is a far different animal than Java in that regard.

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Rune

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Originally posted by Grizzly:
I have to disagree with you on the ++, and -- usage on pointers. Imagine you wanted to read in 800 seperate scanf's from the keyboard. Easiest way to do this would be to create a big-*** array, and use pointer's in a for loop to increment the location in the array. Like this:

int x, *ptr, array[800];
for(x = 0, ptr = &array[0]; x < 800; x++, ptr++)
scanf("%d", ptr);

Little crap like that make the increment and decrement operators useful with pointers. But you're right, makes for some amazingly cryptic code as it gets more complicated https://www.sharkyforums.com/images/.../2005/06/4.gif

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What about doing it like this?

int x, array[800];
for(x = 0, x < 800; x++)
scanf("%d", &array[x]);

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Originally posted by Humus:
What about doing it like this?

int x, array[800];
for(x = 0, x < 800; x++)
scanf("%d", &array[x]);

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Compilers used to (I don't know if they've improved this or not) have a harder time optimizing that code. An array based lookup like that will lead to an additional add instruction. Add is way more costly than inc.

In addition, using the counter variable inside the forloop forces the compiler to count the way indicated. An extra instruction could've been saved had the compiler been given the opportunity to count backwards (i.e. count down from 800 towards 0). Delphi frequently uses this form of optimizations on simple for loops (I dunno if any C for loop can be characterized as "simple" though and benefit from such optimizations).

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Rune

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Originally posted by BikeDude:
Compilers used to (I don't know if they've improved this or not) have a harder time optimizing that code. An array based lookup like that will lead to an additional add instruction. Add is way more costly than inc.

In addition, using the counter variable inside the forloop forces the compiler to count the way indicated. An extra instruction could've been saved had the compiler been given the opportunity to count backwards (i.e. count down from 800 towards 0). Delphi frequently uses this form of optimizations on simple for loops (I dunno if any C for loop can be characterized as "simple" though and benefit from such optimizations).
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Rune

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At least the MSVC compiler seams to make a better job if you avoid direct pointer aritmetic. I have tried to optimize my code many time by using ++ or -- on pointers just to find out that my code became slower. Most compilers of today are smart enough to optimize indexing in for loops with pointer incrementation, so there's seldom any advantage of using ++ on pointers.

Btw, ADD isn't "way more costly" than INC. They use the same hardware. The only difference is that INC is a one byte instruction while ADD is two, so it can only help the caching slightly in some situations.

It isn't necessarily so that C programs run faster than anything short of assembly language. Some counter-examples:
- One friend of mine worked on porting a military battlefield simulator from FORTRAN to C. The C version ran a lot slower. That was probably partly due to bottlenecks with the database it was using, but also due to the fact that function-call prolog/epilog is typically slower in C (FORTRAN living without stack frames)
- C++ programs are often as quick or quicker than their C equivalents. That's because it's easier to choose a good data structure/algorithm in C++ than in C (of course, it's also easier to rely on inefficient libraries as well).

Then again, more compiler writers have put more effort into developing C compilers than they have for any other language, so there's something in it, I just wouldn't make it an absolute rule.

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Originally posted by BikeDude:
Compilers used to (I don't know if they've improved this or not) have a harder time optimizing that code. Rune

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Modern optimizing compilers can indeed optimize code that uses array notation. They've come a long way since the ++ notation was introduced as a hint to use the PDP11's auto-increment addressing mode. And, since modern processors translate x86 instructions to RISC-like ops before execution, it's not necessarily so that an inc instruction will work faster than an add.

Back in the day when I did Pascal it was very slow... Delphi is probably at least 10,000 times better then Pascal on a DG2000 mainframe though:P The thing I can do in C that I can't do in Pascal, or Java, or anything else mostly pertains to the programming I do on small microcontrollers and pic's. And that is mostly because somebody wrote compilers for C for those chips. It is probably my misconsception but I have always considered pascal a learning language developed for educational purposes (which was it's original intent) and not a high powered language for product development. I also know that educators have mostly migrated from Pascal to C or C++ because they feel it is more worth while for there students to know. Once again, I am not saying that Pascal or Delphi is old and crappy by any means, I haven't actually ever used Delphi. I just know that as far as the world of business goes most new code is being generated in C or C++ and they are both definitly important languages to know and understand.

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My computer said "WindowsME/2000 or better" so I installed Linux.

[This message has been edited by jtshaw (edited October 30, 2000).]

[This message has been edited by jtshaw (edited October 30, 2000).]

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Originally posted by jtshaw:
I also know that educators have mostly migrated from Pascal to C or C++ because they feel it is more worth while for there students to know.

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AFAIK the educational sector is in complete disarray. I suspect you'll find just as many institutions teaching Java and/or VB as you'll find C++... And the reasons given doesn't have to make sense.

Plus, the same probably goes for the choice of OS. There is probably more demand for NT knowledge these days, but some schools still prefer to push a particular brand of UNIX (be it SUN Solaris, Linux, HP-UX or [insert your favourite flavour of UNIX here]). It doesn't necessarily reflect the real world of yesterday, today or tomorrow. (and I don't mind, learning C and UNIX during my school days never hurt me any)

One of the most popular development environments is Visual Basic. People actually try to use VB to build realworld applications and haven't caught on to the fact that MS has not released anything internationally written using their own tool (someone once mentioned "MS Money", but it's not available overseas so I've never seen it). In fact, the author of "Hardcore VB" once commented that he had to explain a particular piece of BASIC syntax to one of MS' VB developers who had never touched a line of BASIC in his entire life... But still, people insist on using it.

Anyway, a good teacher would probably prefer the most featureless development tool there is, so that the pupil can focus on the basics rather than get caught up with a particular (and extensive) library. I suspect when you say C++, they'd rather go for a stripped down Borland C++ version rather than a full blown C++ Builder with bells on.

YMMV of course...

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Rune

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Originally posted by jtshaw:
Back in the day when I did Pascal it was very slow... Delphi is probably at least 10,000 times better then Pascal on a DG2000 mainframe though:P The thing I can do in C that I can't do in Pascal, or Java, or anything else mostly pertains to the programming I do on small microcontrollers and pic's. And that is mostly because somebody wrote compilers for C for those chips. It is probably my misconsception but I have always considered pascal a learning language developed for educational purposes (which was it's original intent) and not a high powered language for product development. I also know that educators have mostly migrated from Pascal to C or C++ because they feel it is more worth while for there students to know. Once again, I am not saying that Pascal or Delphi is old and crappy by any means, I haven't actually ever used Delphi. I just know that as far as the world of business goes most new code is being generated in C or C++ and they are both definitly important languages to know and understand.

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The real power of Delphi is productivity. You can smash together a complete windows app with a lot of buttons and controls in notime. https://www.sharkyforums.com/images/.../2005/06/5.gif It's way more easy than VC++.

If you want to play, start with something working and see how it works. You can get the Quake source code and look at that (though the DOOM code is easier to understand), or work with an existing package you can use:
http://crystal.linuxgames.com/

Building a 3D engine is the task of several highly talented and trained programmers. There are MANY engines already out there.

David Stidolph

Ya, that is why I like Borland C++ Builder a lot. It works very similar to Delphi or so I hear (not surprising though now is it) and it allows me to code in C++. Microsoft was stupid when the didn't allow VB style form building and such with Visual C++. In my opinion there isn't much Visual about VC++. I don't wanna have to learn mfc just to throw a couple windows on the screen.
Also, about the whole Jake's Challenge thing... Putting Delphi up against VC++ doesn't prove that Object Pascal compiles to better optimized source code then C. I personnally use C or C++ for most everything and wouldn't touch a MS product for development. Anyway, the entire of purpose of this thread was about 3D games were are virtually all written in C or C++ and always have been.

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Originally posted by Humus:
The real power of Delphi is productivity. You can smash together a complete windows app with a lot of buttons and controls in notime. https://www.sharkyforums.com/images/.../2005/06/5.gif It's way more easy than VC++.

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My computer said "WindowsME/2000 or better" so I installed Linux.

[This message has been edited by jtshaw (edited October 31, 2000).]

Quote:

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Originally posted by jtshaw:
Ya, that is why I like Borland C++ Builder a lot. It works very similar to Delphi or so I hear (not surprising though now is it) and it allows me to code in C++. Microsoft was stupid when the didn't allow VB style form building and such with Visual C++. In my opinion there isn't much Visual about VC++. I don't wanna have to learn mfc just to throw a couple windows on the screen.
Also, about the whole Jake's Challenge thing... Putting Delphi up against VC++ doesn't prove that Object Pascal compiles to better optimized source code then C. I personnally use C or C++ for most everything and wouldn't touch a MS product for development. Anyway, the entire of purpose of this thread was about 3D games were are virtually all written in C or C++ and always have been.

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I have to agree with this, I wish there was a quick way to throw up some GUI items in Visual C++. At work we are currently using Java. It is so easy to slap together a GUI in java, I dont have much experience with Delphi, but I would love to see C++ have a really good way of developing a GUI. We have been talking about our next project and probably going with C++ so does anyone know of any compilers that you can prototype a GUI rather easily?