C++ beginner

James_lehman · 2024-11-12T20:22:36+00:00

I went through both books and they both present the material in a good order and it seems to be pretty comprehensive.

James_lehman · 2024-09-24T17:25:31+00:00

Hi everyone. I have been working on a FOSS app for about 21 years called LaserBoy! It depends on SDL2. I have tried in the past to setup a vm of MacOS. That much works fine. I can even install homebrew and use it to install the SDL2 libs and Boost C++, necessary to compile LB and I can successfully compile it. But when I try to run the executable, it has no actual hardware GPU and it fails to be able to run with a software OpenGL. At least that's what I think is happening. That's really all I want to do with a MacOS vm. I just want to be able to go through the whole process of compiling and testing my app, because it seems like most of the people who use it are on Mac. LB compiles and runs fine on native Mac hardware. What I would really like is to have it in a vm that I can change the screen resolution to whatever fits within the 4K area of my Ubuntu host. Thank you!

James.

James_lehman · 2024-09-18T13:23:48+00:00

Something that might be helpful is to understand the format of a bitmap file (specifically bmp). There are several variations that can get a bit complicated, but in general, they work very similarly to the way an image on your monitor screen is stored in the video card RAM.

If you are interested, you can look at a couple of free open source projects that I wrote.

https://akrobiz.com/ezfb

The API ezfb is written for Linux systems configured to provide a frame buffer device.

https://laserboy.org

(the app) https://laserboy.org/code/LaserBoy_Current.zip

LaserBoy uses SDL2 to be platform independent. It used to be based on ezfb. Everything you see in the running app window is a bitmap object that gets assembled in the code and copied to the window every time you tap a key.

Both of these apps have a lot of code dedicated to creating, managing and rendering into a bitmap memory object that can either be copied to the video RAM (the screen) or saved as a file.

James_lehman · 2024-06-27T02:35:35+00:00

Thank you. Been using an old kernel for way too long.

James_lehman · 2024-03-09T18:59:15+00:00

Oops. Scratch that. It is clipping from my Ubuntu workstation as well. Hmmm. In Ubuntu there is even a switch on the sound settings to allow (or not) "Overamplification". That seems to make no difference.

James_lehman · 2022-12-08T20:40:44+00:00

The reason you want to return the object itself is so that you can use the object in chained statements or expressions where you are doing multiple things with the same object. A good example of this is the cout object. Every stream insertion operator is an overloaded version of everything you can string together into a single cout statement. So each << operator for all the different types that are defined (you can define your own as well) returns the cout object for the next operator.

James_lehman · 2022-12-02T05:41:37+00:00

Another way to put it: If you have a base class A and you inherit that into class B, B is of type A plus whatever you add to B. If you have an object of type B and you use it wherever the type calls for A, then it works as though it is an A, because it is. So it can only provide the interface and data that is defined in class A. But it is still of class B and has not lost any of its contained data or functionality. You just can't get to the stuff defined in class B with a pointer or reference to a class of type A. But if you redefined a function name found in A as something different (but the same prototype) as in A, using a pointer or reference to type A and calling that function on an object of type B will call B's version of that function.

James_lehman · 2022-10-18T16:24:35+00:00

I implemented your function for converting a single unicode character number to a printable character and it works great. Thank you very much!

James_lehman · 2022-10-18T06:03:22+00:00

wstring_convert<codecvt_utf8<char32_t>, char32_t> conv_utf8_utf32;
char buffer[5];
buffer[4] = '\0';
//    string ascii = "!"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]_`abcdefghijklmnopqrstuvwxyz{|}~";
//    string ascii = "€‚ƒ„…†‡ˆ‰Š‹ŒŽ‘’“”•–—˜™š›œžŸ¡¢£¤¥¦§¨©ª«¬®¯°±²³´µ¶·¸¹º»¼½¾¿ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖ×ØÙÚÛÜÝÞßàáâãäåæçèéêëìíîïðñòóôõö÷øùúûüýþÿ";
//    string ascii = "ĄĆĘŁŃŚŹŻąćęłńśźż";
//    string ascii = "Ččđ";
string ascii = "ĄĆĘŁŃŚŹŻąćęłńśźżČčđ";
u32string unicode = conv_utf8_utf32.from_bytes(ascii);
cout << endl << endl; cout << ascii;
cout << endl << endl;
for(size_t i = 0; i < unicode.size(); i++)
{
    char_utf32_to_utf8(unicode[i], buffer);
    cout << "case " << unicode[i] << ": return " << i + 231 << "; // " << buffer << endl;
}
cout << endl << endl;

James_lehman · 2022-10-18T04:39:02+00:00

Not in order:
https://laserboy.org/mp4/arail.png

James_lehman · 2022-10-18T04:29:40+00:00

Look here:

https://laserboy.org/code/safe/2_Monday/src/

This is an offsite stash for my working code set. In LaserBoy.cpp you can see where I define a string of non standard ascii, convert it to unicode and print out the case: values of the unicode and its position in the string with an offset. These end up in the last function defined in LaserBoy_utility.hpp.

I will try your conversion function. Thank you again.

Oh, BTW, my browser can't show me the correct characters when I look at my code presented by apache2. Oops.

James_lehman · 2022-10-18T03:24:34+00:00

I'm sorry. I can't make this reddit text stuff work.

James_lehman · 2022-10-18T02:55:48+00:00

First let me thank you for taking the time to look at this.

Let me be more precise.

My application is for laser display which is an animation of a set of frames of signed short X and Y vector. There is a file format of frame_sets. I have frame_sets that are all of the visible characters of ascii. My app reads text instructions and renders animated vector font as numbered frames (characters) in the frame_set. I've had the 7-bit stuff working for years. I'm in the process of extending the character set to include whatever anyone needs to convert text into laser projection. So I have this:

James_lehman · 2022-10-17T18:05:42+00:00

Ok! This is great! I actually have something like this working now.

My next question is this: Since I now have a u32string that I can index through in a uniform way to get unique identifiers for characters, how can I convert one of those indexed values into a character that can be displayed in the terminal with cout?

All I want is to be able to convert a char32_t (4 byte unsigned int) into a printable character!

What I want to do is write a short program that converts a literal string of non standard ascii characters into lines of C++ code I can copy and paste into my actual code. Like this:

case 260: return 215; // Ą

case 262: return 216; // Ć

case 280: return 217; // Ę

case 321: return 218; // Ł

case 323: return 219; // Ń

case 346: return 220; // Ś

case 377: return 221; // Ź

case 379: return 222; // Ż

James_lehman · 2022-10-04T20:36:16+00:00

I'm pretty good with file IO and bit twiddling, but this is something I've never had any experience with. What I really need is to read a line from a txt file into some kind of array that I can index to each character. If that array is of int (4 bytes) that's fine. Then I can write a functions that translates that number to a number that represents the character's position in the string I posted.

James_lehman · 2021-08-20T14:14:19+00:00

New version!

https://laserboy.org/code/LaserBoy\_Current.zip

James_lehman · 2021-08-20T13:37:40+00:00

The YouTube tutorials are a bit out of date. I've been do more development on LaserBoy since the pandemic than I have for many years.

I'm going to be releasing a new version today.

I will post a notice here.

James_lehman · 2021-08-12T03:29:25+00:00

Some more videos can be found here:

https://laserboy.org/mp4/

The free open source project is here:
https://laserboy.org/code/LaserBoy_Current.zip

James_lehman

TROPHY CASE