Control characters are non-printing characters used to send signals to the output terminal.
Control characters are generally non-printing characters that are used to send signals to the output terminal.
More information is available on Wikipedia.
Questions tagged [control-characters]
198 questions
564
votes
12 answers
What are carriage return, linefeed, and form feed?
What is the meaning of the following control characters:
Carriage return
Line feed
Form feed
ashna
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43
votes
2 answers
What are the file/group/record/unit separator control characters and their usage?
Unicode defines several control characters from ASCII. http://www.unicode.org/charts/PDF/U0000.pdf
I see many control characters are widely used but I really don't see where "information separators" are used. (U+001C~U+001F)
What are they? What's…
eonil
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31
votes
2 answers
Finding the Values of the Arrow Keys in Python: Why are they triples?
I am trying to find the values that my local system assigns to the arrow keys, specifically in Python. I am using the following script to do this:
import sys,tty,termios
class _Getch:
def __call__(self):
fd =…
Newb
- 2,454
- 2
- 18
- 31
30
votes
4 answers
Match non printable/non ascii characters and remove from text
My JavaScript is quite rusty so any help with this would be great. I have a requirement to detect non printable characters (control characters like SOH, BS etc) as well extended ascii characters such as Ž in a string and remove them but I am not…
Grant Doole
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26
votes
5 answers
Why is '\x' invalid in Python?
I was experimenting with '\' characters, using '\a\b\c...' just to enumerate for myself which characters Python interprets as control characters, and to what. Here's what I found:
\a - BELL
\b - BACKSPACE
\f - FORMFEED
\n - LINEFEED
\r - RETURN
\t…
PaulMcG
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- 14
- 81
- 122
22
votes
4 answers
Discretionary line break in HTML?
I'm looking for a way to specify where a line should break if it cannot fit on its line in a way similar to (soft/discretionary hyphen), but with a space. I tried googling it but didn't get many relevant hits (mostly for InDesign despite…
Jakob Jingleheimer
- 29,050
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- 121
21
votes
2 answers
What does the "^@" mean in file?
Code:
int fd;
fd = open("fruit", O_WRONLY);
write(fd, "apple", sizeof("apple"));
close(fd);
I compile it with
$ gcc test.c -o test
and run as
$ ./test
Then I open the fruit file, and I see the following in the file:
apple^@
What does the ^@…
Ren
- 2,488
- 1
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- 36
15
votes
3 answers
Removing control characters from a UTF-8 string
I found this question but it removes all valid utf-8 characters also (returns me a blank string, while there are valid utf-8 characters plus control characters). As I read about utf-8, there's not a specific range for control characters and each…
Xaqron
- 26,135
- 39
- 130
- 194
15
votes
4 answers
Java: detect control characters which are not correct for JSON
I am reinventing the wheel and creating my own JSON parse methods in Java.
I am going by the (very nice!) documentation on json.org. The only part I am unsure about is where it says "or control character"
Since the documentation is so clear, and…
700 Software
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14
votes
3 answers
XmlTextWriter incorrectly writing control characters
.NET's XmlTextWriter creates invalid xml files.
In XML, some control characters are allowed, like 'horizontal tab' ( ), but others are not, like 'vertical tab' ( ). (See spec.)
I have a string which contains a UTF-8 control character that is…
Tom Lokhorst
- 12,397
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- 69
14
votes
9 answers
What does PuTTY send when I press Enter key?
I am trying desperately to get a Bluetooth dongle working with my Arduino but I can't send it a command that it needs. I can use it when I plug it into my computer via a USB to UART chip and send the command (C) from PuTTY and then press Enter.
The…
Sponge Bob
- 1,185
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12
votes
6 answers
Is there a faster way to clean out control characters in a file?
Previously, I had been cleaning out data using the code snippet below
import unicodedata, re, io
all_chars = (unichr(i) for i in xrange(0x110000))
control_chars = ''.join(c for c in all_chars if unicodedata.category(c)[0] == 'C')
cc_re =…
alvas
- 94,813
- 90
- 365
- 641
11
votes
1 answer
What is the purpose of Unicode "Backspace" U+0008?
What is the purpose of the Unicode Character 'BACKSPACE' (U+0008) in programming? What applications can it be used for?
skibulk
- 2,768
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- 39
11
votes
3 answers
cscript - print output on same line on console?
If I have a cscript that outputs lines to the screen, how do I avoid the "line feed" after each print?
Example:
for a = 1 to 10
WScript.Print "."
REM (do something)
next
The expected output should be:
..........
Not:
.
.
.
.
.
.
.
.
.
.
In…
Guy
- 9,125
- 7
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- 42
10
votes
5 answers
ASCII control character html input text
I'm trying to process input from a barcode scanner in a javascript browser app. The scanner output is a string of characters, which also contains at least one Group Separator character (ASCII 29).
When I direct the input to i.e. notepad++, the…
user2007080
- 125
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- 7