Let's say I want to assign a text (which contains many double quotes) into variable. However, the only way seems to manually escape:
string t = "Lorem \"Ipsum\" dummy......
//or//
string t = #"Lorem ""Ipsum"" dummy.....
Is there any way to avoid manual escaping, and instead use something universal (which I dont know in C#) keywoard/method to do that automatically? In PHP, it's untoldly simple, by just using single quote:
$t = 'Lorem "Ipsum" dummy .......
btw, please don't bomb me with critiques "Why do you need to use that" or etc. I need answer to the question what I ask.
I know this answer may not be satisfying, but C# sytnax simply won't allow you to do such thing (at the time of writing this answer).
I think the best solution is to use resources. Adding/removing and using strings from resources is super easy:
internal class Program
{
private static void Main(string[] args)
{
string myStringVariable = Strings.MyString;
Console.WriteLine(myStringVariable);
}
}
The Strings is the name of the resources file without the extension (resx):
MyString is the name of your string in the resources file:
I may be wrong, but I conjecture this is the simplest solution.
No. In C# syntax, the only way to define string literals is the use of the double quote " with optional modifiers # and/or $ in front. The single quote is the character literal delimiter, and cannot be used in the way PHP would allow - in any version, including the current 8.0.
Note that the PHP approach suffers from the need to escape ' as well, which is, especially in the English language, frequently used as the apostrophe.
To back that up, the EBNF of the string literal in current C# is still this:
regular_string_literal '"' { regular_string_literal_character } '"'
The only change in the compiler in version 8.0 was that now, the order of the prefix modifiers $ (interpolated) and # (verbatim) can be either #$ or $#; it used to matter annoyingly in earlier versions.
Alternatives:
Save it to a file and use File.ReadAllText for the assignment, or embed it as a managed ressource, then the compiler will provide a variable in the namespace of your choice with the verbatim text as its runtime value.
Or use single quotes (or any other special character of your choice), and go
var t = #"Text with 'many quotes' inside".Replace("'", #"""");
where the Replace part could be modeled as an extension to the String class for brevity.
Related
I'm translating a Unity game and some of the lines go like
Unlock at XXXX
where "XXXX" is replaced at runtime by an arbitrary substring. Easy enough to replace the wildcards, but to translate the quote, I can't simply concatenate a + b, as some languages will have the value before or inside the string. I figured I needed to, effectively, de-replace it, ie isolate and keep the substring and translate whatever's around it.
Problem is that while I can easily do the second part, I can't think of any avenues for the first. I know to get the character index of what I'm looking for, but the value takes up an arbitrary number of characters, and I can't use whitespace since some languages don't use it. Can't use digit detection since not all of the values are going to be numbers. I tried asking Google, but I couldn't translate "find whatever replaces a wildcard" into something keyword-searchable.
In short, what I'm looking for is a way to find the "XXXX" (the easy part) and then find whatever replaces it in the string (the less-easy part).
Thanks in advance.
I eventually found a workaround, thanks to everybody's kind advice. I stored the substring and referred to it in a special translation method that does take in a value. Thanks for your kind help, everybody.
public static string TranslateWithValue (string text, string value, int language) {
string sauce = text.Replace (value, "XXXX");
sauce = Translate (sauce, language);
sauce = sauce.Replace ("XXXX", value);
return sauce;
}
Usually, I use string.Format in such cases. In your case, I'd declare 2 localizeable strings:
string unlockFormat = "Unlock at {0}";
string unlockValue = "next level";
When you need the unlock condition displayed, you can combine the strings like that:
string unlockCondition = string.Format(unlockFormat, unlockValue);
which will produce the string "Unlock at next level".
Both unlockFormat and unlockValue can be translated, and the translator can move {0} wherever needed.
I am reading a C# source file.
When I encounter a string, I want to get it's value.
For instance, in the following example:
public class MyClass
{
public MyClass()
{
string fileName = "C:\\Temp\\A Weird\"FileName";
}
}
I would like to retrieve
C:\Temp\A Weird"FileName
Is there an existing procedure to do that?
Coding a solution with all the possible cases should be quite tricky (#, escape sequences. ...).
I am convinced such procedure exists...
I would like to have the dual function too (to inject a string into a C# source file)
Thanks in advance.
Philippe
P.S:
I gave an example with a filename, but I look for a solution working for all kinds of strings.
I'm pretty sure you can use CodeDOM to read a C# code file and parse its elements. It generates a code tree, and then you can look for nodes representing strings.
http://www.codeproject.com/Articles/2502/C-CodeDOM-parser
Other CodeDom parsers:
http://www.codeproject.com/Articles/14383/An-Expression-Parser-for-CodeDom
NRefactory: https://github.com/icsharpcode/NRefactory and http://www.codeproject.com/Articles/408663/Using-NRefactory-for-analyzing-Csharp-code
There is a way of extracting these strings using a regular expression:
("(\\"|[^"])*")
This particular one works on your simple example and gives the filename (complete with leading and trailing quote characters); whether it would work on more complex ones I can't easily tell unfortunately.
For clarity, (\\"|[^"]) matches any character apart from ", except where it has a leading \ character.
Just use ".*" Regex to match all string values, then remove trailing inverted commas and unescape it.
this will allow \" and "" characters inside your string
so both "C:\\Temp\\A Weird\"FileName" and "Hello ""World""" will match
Is there a heredoc notation for strings in C#, preferably one where I don't have to escape anything (including double quotes, which are a quirk in verbatim strings)?
As others have said, there isn't.
Personally I would avoid creating them in the first place though - I would use an embedded resource instead. They're pretty easy to work with, and if you have a utility method to load a named embedded resource from the calling assembly as a string (probably assuming UTF-8 encoding) it means that:
If your embedded document is something like SQL, XSLT, HTML etc you'll get syntax highlighting because it really will be a SQL (etc) file
You don't need to worry about any escaping
You don't need to worry about either indenting your document or making your C# code look ugly
You can use the file in a "normal" way if that's relevant (e.g. view it as an HTML page)
Your data is separated from your code
Well even though it doesn't support HEREDOC's, you can still do stuff like the following using Verbatim strings:
string miniTemplate = #"
Hello ""{0}"",
Your friend {1} sent you this message:
{2}
That's all!";
string populatedTemplate = String.Format(miniTemplate, "Fred", "Jack", "HelloWorld!");
System.Console.WriteLine(populatedTemplate);
Snagged from:
http://blog.luckyus.net/2009/02/03/heredoc-in-c-sharp/
No, there is no "HEREDOC" style string literal in C#.
C# has only two types of string literals:
Regular literal, with many escape sequences necessary
Verbatim literal, #-quoted: doublequotes need to be escaped by doubling
References
csharpindepth.com - General Articles - Strings
MSDN - C# Programmer's Reference - Strings
String literals are of type string and can be written in two forms, quoted and #-quoted.
November 2022 update:
Starting with C# 11 this is now possible using Raw string literals:
var longMessage = """
This is a long message.
Some "quoted text" here.
""";
As we all know,we can use
string aa=#"E:\dev_workspace1\AccessCore\WebRoot\DataFile"
in c# in order not to double the '\'.
But how to do in java?
Unfortunately, there is no full-string escape operator in Java. You need to write the code as:
String aa = "E:\\dev_workspace1\\AccessCore\\WebRoot\\DataFile";
There is no whole string escape operator but, if it's for file access, you can use a forward slash:
String aa="E:/dev_workspace1/AccessCore/WebRoot/DataFile";
Windows allows both forward and backward slashes as a path separator. It won't work if you pass the path to an external program that mangles with it and fails, but that's pretty rare.
Might not be a direct answer to your question, but I feel this should be pointed out:
There's a system-dependent default name-separator character.
The really system-independent way is to do this:
String aa = "E:/dev_workspace1/AccessCore/WebRoot/DataFile";
String output = aa.replace('/', File.separatorChar);
It will give you
"E:\dev_workspace1\AccessCore\WebRoot\DataFile"
on Windows and
"E:/dev_workspace1/AccessCore/WebRoot/DataFile"
just about everywhere else.
If you write a path, you should use the '/' as path-separator under Java. The '/' is the official path-separator under Java and will be converted to the appropriate separator for the platform (\ under windows, / under unix). The rest of the string is unchanged if passed to the system, so the '\' also works under windows. But the correct way to represent this path is "E:/dev_workspace1/AccessCore/WebRoot/DataFile".
If you want to represent a '\' in a Java-String you have to escape it with another one: "This String contains a \".
In C#, if you want a String to be taken literally, i.e. ignore escape characters, you can use:
string myString = #"sadasd/asdaljsdl";
However there is no equivalent in Java. Is there any reason Java has not included something similar?
Edit:
After reviewing some answers and thinking about it, what I'm really asking is:
Is there any compelling argument against adding this syntax to Java? Some negative to it, that I'm just not seeing?
Java has always struck me as a minimalist language - I would imagine that since verbatim strings are not a necessity (like properties for instance) they were not included.
For instance in C# there are many quick ways to do thing like properties:
public int Foo { get; set; }
and verbatim strings:
String bar = #"some
string";
Java tends to avoid as much syntax-sugar as possible. If you want getters and setters for a field you must do this:
private int foo;
public int getFoo() { return this.foo; }
public int setFoo(int foo) { this.foo = foo; }
and strings must be escaped:
String bar = "some\nstring";
I think it is because in a lot of ways C# and Java have different design goals. C# is rapidly developed with many features being constantly added but most of which tend to be syntax sugar. Java on the other hand is about simplicity and ease of understanding. A lot of the reasons that Java was created in the first place were reactions against C++'s complexity of syntax.
I find it funny "why" questions. C# is a newer language, and tries to improve in what is seen as shortcomings in other languages such as Java. The simple reason for the "why" question is - the Java standard does not define the # operator such as in C#.
Like said, mostly when you want to escape characters is for regexes. In that case use:
Pattern.quote()
I think one of the reasons is that regular expressions (which are a major reason for these kind of String literals) where not part of the Java platform until Java 1.4 (if I remember correctly). There simply wasn't so much of a need for this, when the language was defined.
Java (unfortunately) doesn't have anything like this, but Groovy does:
assert '''hello,
world''' == 'hello,\nworld'
//triple-quotes for multi-line strings, adds '\n' regardless of host system
assert 'hello, \
world' == 'hello, world' //backslash joins lines within string
I really liked this feature of C# back when I did some .NET work. It was especially helpful for cut and pasted SQL queries.
I am not sure on the why, but you can do it by escaping the escape character. Since all escape characters are preceded by a backslash, by inserting a double backslash you can effectively cancel the escape character. e.g. "\now" will produce a newline then the letters "ow" but "\now" will produce "\now"
I think this question is like: "Why java is not indentation-sensitive like Python?"
Mentioned syntax is a sugar, but it is redundant (superfluous).
You should find your IDE handles the problem for you.
If you are in the middle of a String and copy-paste raw text into it, it should escape the text for you.
PERL has a wider variety of ways to set String literals and sometimes wish Java supported these as well. ;)