# in filename using Maxscript - string-literals

Using Maxsctipt: Exporting a file the following code works fine:
caption:"Caption" \
types:"text(*.txt)|*.txt|All|*.*|" \
filename:(sysinfo.currentdir + #"\some_text.txt")
I am wondering what the significance the # symbol has?

From the maxscript help file:
http://docs.autodesk.com/3DSMAX/15/ENU/MAXScript-Help/index.html?url=files/GUID-7F17449E-C377-445C-AC15-CD3BA88A975B.htm,topicNumber=d30e141051
Verbatim String Literals
Verbatim string literals added to MAXScript in 3ds Max 2008 are
prefixed by the '#' character and are NOT expanded even if containing
backslash escape character sequences like '\t', '\n' or '\r'.
Bottomline you don't need to escape characters in the string if there are any "illegal" characters in it, especially helpful when dealing with paths loads of \ 's

Related

R Shiny: Is there any way to read a single backslash in user input?

I'm making a Shiny app that constructs a bash script to run on a cluster (basically just a txt file). One of the user inputs is a curl command (provided by the database where the files are stored) that they can copy/paste into a textInput field in the app. When run on the cluster, it will download the file for further processing. However, the curl command they provide contains several single backslashes. Example:
curl --cookie jgi_session=/api/sessions/ec32f2d578304a9e62b4646ae2bec6d4 --output download.20210731.211924.zip -d "{\"ids\":[\"5d94dc9fc0d65a87debccfd3\"]}" -H "Content-Type: application/json" https://files.jgi.doe.gov/filedownload/
It works fine if I paste this directly into a script or if I manually add in double backslashes, but I want to keep this as user friendly as possible. Every other post I've seen about this just says to use double backslashes, but I'd rather do this automatically if at all possible. So any ideas? I'm open to alternate solutions, less work for the user the better.
Your code is picking up the curl line as escaped characters. When you write to file, those escaped characters get converted to their actual character (i.e \" gets converted to literal ".
To avoid, replace special escaped characters by the character sequence that literally created the escape sequence. So to build \" in the final written string, you have to produce \\" as escaped character sequence (which is what the output of a print commmand should show).
Once way to achieve this for this particular character sequence is
escapedString = gsub('\"', '\\"', curlString)
Note that, in terms of string interpretation, \" is a single character (converting to "), while \\" is a sequence of two characters: an escaped \ and a literal ", converting to \" when written, which is the desired output.

gsub remove backslash and numbers from string [duplicate]

I'm writing strings which contain backslashes (\) to a file:
x1 = "\\str"
x2 = "\\\str"
# Error: '\s' is an unrecognized escape in character string starting "\\\s"
x2="\\\\str"
write(file = 'test', c(x1, x2))
When I open the file named test, I see this:
\str
\\str
If I want to get a string containing 5 backslashes, should I write 10 backslashes, like this?
x = "\\\\\\\\\\str"
[...] If I want to get a string containing 5 \ ,should i write 10 \ [...]
Yes, you should. To write a single \ in a string, you write it as "\\".
This is because the \ is a special character, reserved to escape the character that follows it. (Perhaps you recognize \n as newline.) It's also useful if you want to write a string containing a single ". You write it as "\"".
The reason why \\\str is invalid, is because it's interpreted as \\ (which corresponds to a single \) followed by \s, which is not valid, since "escaped s" has no meaning.
Have a read of this section about character vectors.
In essence, it says that when you enter character string literals you enclose them in a pair of quotes (" or '). Inside those quotes, you can create special characters using \ as an escape character.
For example, \n denotes new line or \" can be used to enter a " without R thinking it's the end of the string. Since \ is an escape character, you need a way to enter an actual . This is done by using \\. Escaping the escape!
Note that the doubling of backslashes is because you are entering the string at the command line and the string is first parsed by the R parser. You can enter strings in different ways, some of which don't need the doubling. For example:
> tmp <- scan(what='')
1: \\\\\str
2:
Read 1 item
> print(tmp)
[1] "\\\\\\\\\\str"
> cat(tmp, '\n')
\\\\\str
>

Difference between \\ vs \ backreference for regex in r [duplicate]

I'm writing strings which contain backslashes (\) to a file:
x1 = "\\str"
x2 = "\\\str"
# Error: '\s' is an unrecognized escape in character string starting "\\\s"
x2="\\\\str"
write(file = 'test', c(x1, x2))
When I open the file named test, I see this:
\str
\\str
If I want to get a string containing 5 backslashes, should I write 10 backslashes, like this?
x = "\\\\\\\\\\str"
[...] If I want to get a string containing 5 \ ,should i write 10 \ [...]
Yes, you should. To write a single \ in a string, you write it as "\\".
This is because the \ is a special character, reserved to escape the character that follows it. (Perhaps you recognize \n as newline.) It's also useful if you want to write a string containing a single ". You write it as "\"".
The reason why \\\str is invalid, is because it's interpreted as \\ (which corresponds to a single \) followed by \s, which is not valid, since "escaped s" has no meaning.
Have a read of this section about character vectors.
In essence, it says that when you enter character string literals you enclose them in a pair of quotes (" or '). Inside those quotes, you can create special characters using \ as an escape character.
For example, \n denotes new line or \" can be used to enter a " without R thinking it's the end of the string. Since \ is an escape character, you need a way to enter an actual . This is done by using \\. Escaping the escape!
Note that the doubling of backslashes is because you are entering the string at the command line and the string is first parsed by the R parser. You can enter strings in different ways, some of which don't need the doubling. For example:
> tmp <- scan(what='')
1: \\\\\str
2:
Read 1 item
> print(tmp)
[1] "\\\\\\\\\\str"
> cat(tmp, '\n')
\\\\\str
>

How to include multiple backslashes in Unix Korn Shell

I have the following variables in Unix Korn Shell
host=nyc43ksj
qry_dir='\test\mydoc\mds'
fullpath="\\$host\$qry_dir"
echo "$fullpath"
When I execute the above, I get output such as \nyc43ksj\qrydir.
It looks like the backslashes are used as escape characters.
I tried changing fullpath as follows:
fullpath="\\$host\\$qry_dir"
echo "$fullpath"
This time I get \nyc43ksj\test\mydoc\mds. However, the two backslashes at the beginning are not display as two backslashes. How can get the fullpath as \\nyc43ksj\test\mydoc\mds (two backslashes at the beginning).
In a string, the \ (backslash) character acts as an escape character (as you mention), and the second backslash instructs the shell to put in an actual backslash, as opposed to some special character.
If you want to have two actual backslash characters in the string in sequence, you will need to put \\\\ in the string, so:
fullpath="\\\\$host\\$qry_dir"

How to escape backslashes in R string

I'm writing strings which contain backslashes (\) to a file:
x1 = "\\str"
x2 = "\\\str"
# Error: '\s' is an unrecognized escape in character string starting "\\\s"
x2="\\\\str"
write(file = 'test', c(x1, x2))
When I open the file named test, I see this:
\str
\\str
If I want to get a string containing 5 backslashes, should I write 10 backslashes, like this?
x = "\\\\\\\\\\str"
[...] If I want to get a string containing 5 \ ,should i write 10 \ [...]
Yes, you should. To write a single \ in a string, you write it as "\\".
This is because the \ is a special character, reserved to escape the character that follows it. (Perhaps you recognize \n as newline.) It's also useful if you want to write a string containing a single ". You write it as "\"".
The reason why \\\str is invalid, is because it's interpreted as \\ (which corresponds to a single \) followed by \s, which is not valid, since "escaped s" has no meaning.
Have a read of this section about character vectors.
In essence, it says that when you enter character string literals you enclose them in a pair of quotes (" or '). Inside those quotes, you can create special characters using \ as an escape character.
For example, \n denotes new line or \" can be used to enter a " without R thinking it's the end of the string. Since \ is an escape character, you need a way to enter an actual . This is done by using \\. Escaping the escape!
Note that the doubling of backslashes is because you are entering the string at the command line and the string is first parsed by the R parser. You can enter strings in different ways, some of which don't need the doubling. For example:
> tmp <- scan(what='')
1: \\\\\str
2:
Read 1 item
> print(tmp)
[1] "\\\\\\\\\\str"
> cat(tmp, '\n')
\\\\\str
>

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