I have been making a program that outputs each character before a given one to the screen, but... I've been doing it with Brainfuck! :)
I would like to be able to input a character, and see all the characters that come before it. The code I have so far only outputs a space and then waits for the next key press before exiting.
++++++++
[>+++++++++<-]>.>++++++++++[>++++++++++<-]>+.+++++++..+++.>
++++++++[>++++<-]>.>++++++++[>++++++++++++<-]>+.+++ ++++++++++.
----------.>++++++++[>++++<-]>.>++++++++++
[>++++++++<-]>+++++++.
++++++++++++++.>+++++++++[>++++++++++++<-]>.---------.>
++++++++++[>+++++++++++<-]>+.--.--------.>+++
[>++++++++++<-]>+++.>++++++++++
..>+[,[>+>+<<-][>>-<<+>>]>[[-.]<]],
I've tried for ages to figure out what's wrong with this code, but everything I've done has messed it up.
Works for me, try this BF interpreter
------[>++++++++++<+]>--.+<------[>---<+]>.
Related
Hello I'm trying to build a function grapher on the terminal in c++. I want that every time a new function is added the output will be cleared and the new frame will take its place.
I've tried to do system("clear") but I don't want all the terminal to be cleared and only the output stream. I've also thought about printing '\b' a lot of times but that seems inefficient.
I would also like to know how to delete 1 line.
You may try to work with console code.
Console code about cursor
There are two solution.
Here is some C style code, just to demonstate the idea easier, you may convert it into C++ style.
Clear content
//Clear content after (x,y)
printf("\033[%d,%dH\033[J",y,x);
//x the column number,y the row number
Overwrite the content
//Goto (x,y) then print the next frame, it should overwrite the old content
printf("\033[%d,%dH",y,x);
...
//your code to output the next frame
Not sure if this is an appropriate question, but just recently I've noticed that when I run a C++ program in the terminal when it exits it has a % sign after the last output. For example a hello world program says "hello world%". What is this and how do I get rid of it? I'm on OS X, shell is zsh. Unless I am crazy it has never done this until now.
There are two possibilities that I can think of off hand:
1) You aren't printing a carriage return, so the % prompt appears at the end of the printed text instead of on the next line. (Is the % your standard prompt in the shell?)
2) You are printing past the end of a buffer and getting a random character as a result.
I'd guess #1 based on what you describe, but both could cause the behavior.
I use the following lines to output my simulation's progress info in my c++ program,
double N=0;
double percent=0;
double total = 1000000;
for (int i; i<total; ++i)
{
percent = 100*i/total;
printf("\r[%6.4f%%]",percent);
}
It works fine!
But the problem is I see the terminal cursor keeps blinking cyclically through the numbers, this is very annoying, anyone knows how to get rid of this?
I've seen some programs like wget or ubuntu apt, they use progress bar or percentages too, but they seems no blinking cursor issue, I am wondering how did they do that?
Thanks!
You can hide and show the cursor using the DECTCEM (DEC text cursor enable mode) mode in DECSM and DECRM:
fputs("\e[?25l", stdout); /* hide the cursor */
fputs("\e[?25h", stdout); /* show the cursor */
Just a guess: try to use a proper number of '\b' (backspace) characters instead of '\r'.
== EDIT ==
I'm not a Linux shell wizard, but this may work:
system("setterm -cursor off");
// ...display percentages...
system("setterm -cursor on");
Don't forget to #include <cstdlib> or <iostream>.
One way to avoid a blinking cursor is (as suggested) to hide the cursor temporarily.
However, that is only part of the solution. Your program should also take this into account:
after hiding the cursor and modifying the screen, before showing the cursor again move it back to the original location.
hiding/showing the cursor only keeps the cursor from noticeably blinking when your updates take only a small amount of time. If you happened to mix this with some time-consuming process, your cursor will blink.
The suggested solution using setterm is not portable; it is specific to the Linux console. And running an executable using system is not really necessary. But even running
system("tput civis");
...
system("tput cnorm");
is an improvement over using setterm.
Checking the source-code for wget doesn't find any cursor-hiding escape sequences. What you're seeing with its progress bar is that it leaves the cursor in roughly the same place whenever it does something time-consuming. The output to the terminal takes so little time that you do not notice the momentary rewrite of the line (by printing a carriage return, then writing most of the line over again). If it were slower, then hiding the cursor would help — up to a point.
By the way — this cursor-hiding technique is used in the terminal drivers for some editors (vim and vile).
Those apps are probably using ncurses. See mvaddstr
The reason the cursor jumps around is because stdout is buffered, so you don't know actually how many characters are being printed at some point in time. The reason wget does not have a jumping cursor is that they are actually printing to stderr instead, which is unbuffered. Try the following:
fprintf(stderr, "\r[%6.4f%%]", percent);
This also has the advantage of not cluttering the file if you are saving the rest of the output somewhere using a pipe like:
$ ./executable > log.data
Press insert key...if that doesn't work then press the fn key in your keyboard.
This will definitely work
Hope this helps
Is it possible to set how many lines the console will print before it starts to erase the top ones? For example, is it possible to set it to 3 and only make the last 3 lines be visible? So:
std::cout<<"line 1!"<<std::endl;
std::cout<<"line 2!"<<std::endl;
std::cout<<"line 3!"<<std::endl;
std::cout<<"line 4!"<<std::endl;
system("pause");
Would output:
line 3!
line 4!
Press any key to continue...
^without creating a scroll bar on the side.
I've been trying to use Console::BufferHeight but I can't seem to get it to work. This is the only thing I've been able to find that seems to be close to what I want to do: http://msdn.microsoft.com/en-us/library/system.console.bufferheight.aspx But It just shows how to read it, not how to set the size. And for some reason typing just std::cout<<System::Console::BufferHeight; gives me scope errors. Any help would be greatly appreciated. Thanks!
I think you want this:
SetConsoleWindowInfo
Example,
HANDLE hConsole = GetStdHandle(STD_OUTPUT_HANDLE);
SMALL_RECT rect = {0,0, 100, 100};
SetConsoleWindowInfo(hConsole, TRUE, &rect)
Have a look at these as well (experiment with them):
SetConsoleScreenBufferSize()
SetConsoleScreenBufferInfoEx
There is an example on MSDN here.
Im new to programming also, but I tried:
while(!cin.get())
{
}
and it worked,try to place it in the bottom of the code. It will work wonders on your console!
Try changing its position (put it in the middle of the code)
I'd suggest keeping the lines yourself, in a quick class, say that cycles where to put the next line by using an iterator that is always set to point at the next line to be input into.
Next, use FillConsoleOutputCharacter() to print blanks over the lines you previously had printed there.
Then, use SetConsoleCursorPosition() to four(or however many lines you wanted) lines above where you want your input to start, and output each line in you cycle, starting at the one after your iterator. This prints all the lines in order from eldest to youngest.It's been a while, so my knowledge of C++ is kinda hazy, but this should be pretty simple with the standard library and win32 library.
I'm using Code::Blocks on Ubuntu 10.10 (Maverick Meerkat). I have connected a Mac keyboard and set the keyboard settings to "Swiss German Mac". Now whenever I write an equals sign, followed by a space (something like width = 100) I get the error message: stray '\302' in program.
I know this error means that there is a non-standard character in the text file.
When I delete the space character, the program compiles just fine. So that means Code::Blocks adds some sort of special character. But I can't see why this happens. What is the reason?
What character does '\302' stand for?
[UPDATE]
I got a little further investigating the problem. I get this stray when I use the combo Shift + Space. Now that I know it doesn't happen that often any more. But it's still rather annoying especially when writing code... Is there a way to turn off this combo in X11?
[SOLVED]
Thanks to Useless's answer, I was able to solve the "issue". It's more of a feature actually. Shift + space created a spacenolinebreak by default. So by changing the xmodmap with
xmodmap -e "keycode 65 = space space space space space space"
this behavior was overridden and everything works fine now.
Since you're sure it's caused by hitting Shift + Space, you can check what X itself is doing by. First, run xev from the command line, hit Shift + Space and check the output. For example, I see:
$ xev
KeyPress event, serial 29, synthetic NO, window 0x2000001,
root 0x3a, subw 0x0, time 4114211795, (-576,-249), root:(414,593),
state 0x0, keycode 50 (keysym 0xffe1, Shift_L), same_screen YES,
XLookupString gives 0 bytes:
XmbLookupString gives 0 bytes:
XFilterEvent returns: False
KeyPress event, serial 29, synthetic NO, window 0x2000001,
root 0x3a, subw 0x0, time 4114213059, (-576,-249), root:(414,593),
state 0x1, keycode 65 (keysym 0x20, space), same_screen YES,
XLookupString gives 1 bytes: (20) " "
XmbLookupString gives 1 bytes: (20) " "
XFilterEvent returns: False
...
Then, run xmodmap -pk and look up the keycode (space should be 65 as above, but check your xev output).
If you see something like
65 0x0020 (space)
Then X isn't doing this. On the other hand, if I pick a character key which is modified by shift, I see something like this:
58 0x006d (m) 0x004d (M)
If you have two or more keysyms for your keycode, X is the culprit. In that case, something like xmodmap -e 'keycode 65 space' should work.
\302 stands for the octal representation of byte value the compiler encountered. It translates to 11000010 in binary, which makes me think it's the start of a two byte UTF-8 sequence. Then this sequence must be:
11000010 10??????
Which encodes the binary Unicode point 10??????, which can be anything from U+80 to U+BF.
Several characters starting from U+80 are special spaces and breaks which usually are not shown inside a text editor.
Probably it's not your editor, but Xorg, that emits these characters due to your keyboard settings. Try switching to a generic US keyboard and test if the problems persists.
'\302' is C notation for the octal number 3028, which equals C216 and 19410. So it's not ASCII.
Which character it maps to depends on the encoding. In Latin-1, it's the  character, for instance.
I have seen this type of issue when copying and pasting from web pages or other electronic documents. The common culprits would be invalid quotes like ` instead of ', or something alike. Try to use the compiler error to guide you into where in the file the error might be.
That sounds like some kind of encoding issue. I haven't used Code::Blocks for years, so I am not sure if it allows you to pick different encodings.
How about opening your code file with gedit and saving it as UTF-8, and then try again? But it sounds rather strange that you get such an issue using space characters.
I've seen this problem in my Linux box with a Finnish keyboard.
It also happens with Emacs, etc. I don't have a good solution for it, but I guess reports about the fact that it happens elsewhere are also useful...
If you open your file in Emacs and set-buffer-file-coding-system to something like "unix" or some ASCII variety, then when you try to save, it'll warn you that the buffer contains unrepresentable characters and points you to them so you can fix them.
I had the same issue by modified a US ASCII example file.
So I convert it in UTF-8, here are GNU/Linux command:
iconv -c -t us-ascii -f utf-8 source_file -o dest_file
And then add my modifications… no more errors!
To verify initial encoding, use
file -i source_file
I should add a non-ASCII character to allow iconv do the job!!??
I decided to move the file from a MAC book to a Linux box and used email with my icloud.com address. When I opened the transferred file the errors had gone and the file now compiles !