On Unix, when I press up arrow key, it shows this string, but while scanf, it does not take it as input. Please explain how to take it as input. Can we something like compare the character by charater like first ^[ is Esc key and so on?
That's the escape sequence generated by that key. '^[' is CTRL-[ (the ESC character), and the other two characters are '[' and 'A'.
If you want to process them, you'll need to read all three characters and decide that they mean the user pressed the up-arrow key.
Whether or not you can do this with your scanf depends on the format string. I would be using a lower level of character input for this.
I never use [f]scanf in real code since failure results in you not knowing where the input pointer is located. For line-based input, I find it's always better to use fgets and then sscanf the string retrieved.
But, as I said, you should be using getc and its brethren for low-level character I/O. Or find a higher level function such as readline under Linux, or other libraries that know to convert it into special keycodes such as VK_KEY_UP that you can process.
Related
I want the user to enter the input in QLineEdit in the following format
Array {99, 99, 99, 99}
where
1) Array { } is already present in the lineEdit. User only enters comma separated integers.
2) The no. of integers entered may vary.
I tried using setInputMask() for task (1) (backslashes to escape characters)
setInputMask("\A\r\r\a\y\{99\, 99\, 99\}");
But this does not work. Please help.
Disclaimer: This is a partial answer.
For your task (1), you should use double back-slashes to escape them. From the documentation (and in your case), only the following need to be escaped: A, a, {, }.
setInputMask("\\Arr\\ay\\{99\\,99\\,99\\}");
Otherwise, the compiler would (should) warn you about warning: unknown escape sequence: '\S'
With task (2), an idea would be to subclass QLineEdit, and dynamically update the inputMask() at every keypress by overloading keyPressEvent(). Another idea would be to set an input mask with, say, a hundred 99 or x's then to use a regex to validate user input.
I work with knitr() and I wish to transform inline Latex commands like "\label" and "\ref", depending on the output target (Latex or HTML).
In order to do that, I need to (programmatically) generate valid R strings that correctly represent the backslash: for example "\label" should become "\\label". The goal would be to replace all backslashes in a text fragment with double-backslashes.
but it seems that I cannot even read these strings, let alone process them: if I define:
okstr <- function(str) "do something"
then when I call
okstr("\label")
I directly get an error "unrecognized escape sequence"
(of course, as \l is faultly)
So my question is : does anybody know a way to read strings (in R), without using the escaping mechanism ?
Yes, I know I could do it manually, but that's the point: I need to do it programmatically.
There are many questions that are close to this one, and I have spent some time browsing, but I have found none that yields a workable solution for this.
Best regards.
Inside R code, you need to adhere to R’s syntactic conventions. And since \ in strings is used as an escape character, it needs to form a valid escape sequence (and \l isn’t a valid escape sequence in R).
There is simply no way around this.
But if you are reading the string from elsewhere, e.g. using readLines, scan or any of the other file reading functions, you are already getting the correct string, and no handling is necessary.
Alternatively, if you absolutely want to write LaTeX-like commands in literal strings inside R, just use a different character for \; for instance, +. Just make sure that your function correctly handles it everywhere, and that you keep a way of getting a literal + back. Here’s a suggestion:
okstr("+label{1 ++ 2}")
The implementation of okstr then needs to replace single + by \, and double ++ by + (making the above result in \label{1 + 2}). But consider in which order this needs to happen, and how you’d like to treat more complex cases; for instance, what should the following yield: okstr("1 +++label")?
Hi guys I encrypted school project but my AES saved txt has been deleted, I pictured it before and I filled a new file. But new AES key file is not equal to the typed in jpeg file. Which character is wrong I couldn't find it. Could you please help me.
Pic : https://i.stack.imgur.com/pAXzl.jpg
Text file : http://textuploader.com/dfop6
If you directly convert bytes with any value to Unicode you may lose information because some bytes will not correspond to a Unicode character, a whitespace character or other information that cannot be easily distinguished in printed out form.
Of course there may be ways to brute force your way out of this, but this could easily result in very complex code and possibly near infinite running time. Better start over, and if you want to use screen shots or similar printed text: base 64 or hex encode your results; those can be easily converted back.
For example, I have many HTML tabs to style, they use different classes, and will have different backgrounds. Background images files have names corresponding to class names.
The way I found to do it is yank:
.tab.home {
background: ...home.jpg...
}
then paste, then :s/home/about.
This is to be repeated for a few times. I found that & can be used to repeat last substitute, but only for the same target string. What is the quickest way to repeat a substitute with different target string?
Alternatively, probably there are more efficient ways to do such a thing?
I had a quick play with some vim macro magic and came up with the following idea... I apologise for the length. I thought it best to explain the steps..
First, place the text block you want to repeat into a register (I picked register z), so with the cursor at the beginning of the .tab line I pressed "z3Y (select reg z and yank 3 lines).
Then I entered the series of VIM commands I wanted into the buffer as )"zp:.,%s/home/. (Just press i and type the commands)
This translate to;
) go the end of the current '{}' block,
"zp paste a copy of the text in register z,
.,%s/home/ which has two tricks.
The .,% ensures the substitution applies to everything from the start of the .tab to the end of the closing }, and,
The command is incomplete (ie, does not have a at the end), so vim will prompt me to complete the command.
Note that while %s/// will perform a substitution across every line of the file, it is important to realise that % is an alias for range 1,$. Using 1,% as a range, causes the % to be used as the 'jump to matching parenthesis' operator, resulting in a range from the current line to the end of the % match. (which in this example, is the closing brace in the block)
Then, after placing the cursor on the ) at the beginning of the line, I typed "qy$ which means yank all characters to the end of the line into register q.
This is important, because simply yanking the line with Y will include a carriage return in the register, and will cause the macro to fail.
I then executed the content of register q with #q and I was prompted to complete the s/home/ on the command line.
After typing the replacement text and pressing enter, the pasted block (from register z) appeared in the buffer with the substitutions already applied.
At this point you can repeat the last #qby simple typing ##. You don't even need to move the cursor down to the end of the block because the ) at the start of the macro does that for you.
This effectively reduces the process of yanking the original text, inserting it, and executing two manual replace commands into a simple ##.
You can safely delete the macro string from your edit buffer when done.
This is incredibly vim-ish, and might waste a bit of time getting it right, but it could save you even more when you do.
Vim macro's might be the trick you are looking for.
From the manual, I found :s//new-replacement. Seemed to be too much typing.
Looking for a better answer.
I am trying to write a custom report in Spiceworks, which uses SQLite queries. This report will fetch me hard drive serial numbers that are unfortunately stored in a few different ways depending on what version of Windows and WMI were on the machine.
Three common examples (which are enough to get to the actual question) are as follows:
Actual serial number: 5VG95AZF
Hexadecimal string with leading spaces: 2020202057202d44585730354341543934383433
Hexadecimal string with leading zeroes: 3030303030303030313131343330423137454342
The two hex strings are further complicated in that even after they are converted to ASCII representation, each pair of numbers are actually backwards. Here is an example:
3030303030303030313131343330423137454342 evaluates to 00000000111430B17ECB
However, the actual serial number on that hard drive is 1141031BE7BC, without leading zeroes and with the bytes swapped around. According to other questions and answers I have read on this site, this has to do with the "endianness" of the data.
My temporary query so far looks something like this (shortened to only the pertinent section):
SELECT pd.model as HDModel,
CASE
WHEN pd.serial like "30303030%" THEN
cast(('X''' || pd.serial || '''') as TEXT)
WHEN pd.serial like "202020%" THEN
LTRIM(X'2020202057202d44585730354341543934383433')
ELSE
pd.serial
END as HDSerial
The result of that query is something like this:
HDModel HDSerial
----------------- -------------------------------------------
Normal Serial 5VG95AZF
202020% test case W -DXW05CAT94843
303030% test case X'3030303030303030313131343330423137454342'
This shows that the X'....' notation style does convert into the correct (but backwards) result of W -DXW05CAT94843 when given a fully literal number (the 202020% line). However, I need to find a way to do the same thing to the actual data in the column, pd.serial, and I can't find a way.
My initial thought was that if I could build a string representation of the X'...' notation, then perhaps cast() would evaluate it. But as you can see, that just ends up spitting out X'3030303030303030313131343330423137454342' instead of the expected 00000000111430B17ECB. This means the concatenation is working correctly, but I can't find a way to evaluate it as hex the same was as in the manual test case.
I have been googling all morning to see if there is just some syntax I am missing, but the closest I have come is this concatenation using the || operator.
EDIT: Ultimately I just want to be able to have a simple case statement in my query like this:
SELECT pd.model as HDModel,
CASE
WHEN pd.serial like "30303030%" THEN
LTRIM(X'pd.serial')
WHEN pd.serial like "202020%" THEN
LTRIM(X'pd.serial')
ELSE
pd.serial
END as HDSerial
But because pd.serial gets wrapped in single quotes, it is taken as a literal string instead of taken as the data contained in that column. My hope was/is that there is just a character or operator I need to specify, like X'$pd.serial' or something.
END EDIT
If I can get past this first hurdle, my next task will be to try and remove the leading zeroes (the way LTRIM eats the leading spaces) and reverse the bytes, but to be honest, I would be content even if that part isn't possible because it wouldn't be hard to post-process this report in Excel to do that.
If anyone can point me in the right direction I would greatly appreciate it! It would obviously be much easier if I was using PHP or something else to do this processing, but because I am trying to have it be an embedded report in Spiceworks, I have to do this all in a single SQLite query.
X'...' is the binary representation in sqlite. If the values are string, you can just use them as such.
This should be a start:
sqlite> select X'3030303030303030313131343330423137454342';
00000000111430B17ECB
sqlite> select ltrim(X'3030303030303030313131343330423137454342','0');
111430B17ECB
I hope this puts you on the right path.