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The following VB code works correctly and does not flag up any errors.
strLine = strLine.Replace(strLine.LastIndexOf(","), "")
However the same C# code doesn't:
strLine = strLine.Replace(strLine.LastIndexOf(","), "");
This will not compile as it says
The best overloaded method for 'string.Replace(string,string)' has some invalid arguements.
How come this works in VB but not in C#? and how do I fix this?
I thought it might be similar to C# string.Replace doesn't work but it implies that that code will infact complile.
Likewise with other string.Replace questions: string.Replace (or other string modification) not working, it appears they will infact compile, whereas mine will not.
LastIndexOf returns an integer, not a string. Replace takes string, string as parameters, you're passing it int, string, hence the exception The best overloaded method for 'string.Replace(string,string)' has some invalid arguements.
If you're just looking to remove all , use this:
strLine = strLine.Replace(",", "");
Based on your code, you may be only wanting to replace the last instance of , so try this if that's what you want:
StringBuilder sb = new StringBuilder(strLine);
sb[strLine.LastIndexOf(",")] = "";
strLine = sb.ToString();
Reading the documentation, I'm amazed that the first example works at all. string.Replace should receive either a couple of chars or a couple of strings, not an integer and then a string. Pheraps the VB version is converting the integer to its char representation automatically?
In c# the String.Replace's first parameter must be either char or string, but you are using a integer(string.LastIndexOf returns a integer).
Why not just use:
strLine = strLine.Replace(',', '');
Try the following
string.Replace("," , "");
In C# LastIndexOf returns an int, but Replace expects a string or a char as the first argument. I don't know VB to explain why your code works, but I can explain that in C# you can't pass an integer where a string or a char is expected.
In C#, this will do what you want:
strLine = strLine.Replace(',', '');
Hope that helps.
you can use String.Remove
strLine = strLine.Remove(strLine.LastIndexOf(','), 1);
I need to escape chars in a string I have, which content is C:\\blablabla\blabla\\bla\\SQL.exe to C:\blablabla\blabla\bla\SQL.exe so I could throw a process based on this SQL.exe file.
I tried with Mystring.Replace("\\", #"\"); and Mystring.Replace(#"\\", #"\"); but none worked.
How could I do this?
EDITED: Corrected type in string.
I very strongly suspect that you are looking this input string in the Visual Studio debugger and fooling yourself that there are actually 2 \ whereas in reality there aren't. That's the reason why attempting to replace \\ with \ doesn't do anything because in the original string there is no occurrence of \\. And since you are looking the output once again in the debugger, you are once again fooling yourself that there are 2 \.
Visual Studio debugger has this tendency to escape strings. Log it to a file or print to the console and you will see that there is a single \ in your input string and you don't need to replace anything.
It looks like you're trying to replace double backslash (#"\\") in a string with single backslash (#"\"). If so try the following
Mystring = Mystring.Replace(#"\\", #"\");
Note: Are you sure that the string even contains double backslashes? Certain environments will print out a single backslash as a double (debugger for example). Your comment mentioned my approach didn't work. That's a flag that there's not actually a double backslash in your string (else it would work).
The # character specifies a string as a verbatim literal string, but that is when constructing a string. If you use Mystring.Replace("\\", #"\") then nothing will be replaced, essentially, as the two strings are the same.
If you want a string without the escape characters, then either define it with:
string path = #"C:\Some\Directory\And\File.txt";
Or you can replace the \\ with / like so:
path = path.Replace('\\', '/');
It is worth noting, as mentioned by Darin Dimitrov, that the string containing two \ characters is likely just the display of the string (i.e. when using the debugger) and not the actual value of the string.
i think OP is asking how to escape \\ in File Path, if that in the case, as OP is not mentioning where he's trying to use this. so i'm putting a guess.
Then You use Path.Combine() method to get the FileName path.
Path.Combine() Documentation
where are you looking at this output? because it could be the string is what you expect, but viewing the value through the debugger, output window, etc. is escaping the slash
Use something like:
myStr = myStr.Replace(#"\\", #"\");
Make sure you assign the result of Replace method to myStr. Otherwise it goes into void ;)
Try adding "|DataDirectory|\MyFile.xyz" where you need it. It works with connection strings it might work with something else (I haven't really tried to apply it to something else).
I didn't understand what you want, if you just want do get the file name (escape directory chars) you can try:
string fileName = Path.GetFileName(YourString)
Noloman.... when you concatenate are you perhaps missing a "\" when concatenating the directory.. I am assuming that you are trying to join directory + some sub directory.. #noloman keep in mind that in C# "c:\Temp" is written like this "c:\Temp" or #"c:\Temp" one is Literal the other is how to represent a "\" in the legacy way of coding because the "\" is an escape Char and when dealing with directorys we represent all paths and sub paths with "\"
so perhaps by you replacing the "\" you are truly messing up your own expected process
Mystring = Mystring.Replace(#"\\", #"\");
should work for you unless you are truly meaning to do
Mystring = Mystring.Replace(#"\", "\"); which if you believe that you are expecting a "\" to be used to build the directory.. then of course it will not work.. because you have just in essense replaced the backslash with a return char.. I hope that this makes sense to you..
System.IO.Directory.GetCurrentDirectory(); you are using is also an Issue.. SQL Server is not that application thats running the code.. it's your .NET application so you need to either put the location of the SQL Server into a variable, app.config, web.config ect... please edit your question and paste the code that you are using to do what it is that you want to do inregards to the SQL Server Code.. you would probably want to look at the Are you wanting to do something like Process.Start(....) meaning the file name..?
I would like to assign string "{"MY_URL", "MY"}" to string variable. So in my code behind (C#)
I wrote like string str ="{\"MY_URL\", \"MY\"}". When i will assign this to textbox it will print escape character ("\") as well. That i don't want so what i have to do to achieve this??
When i will assign this to textbox it will print escape character ("\") as well.
It shouldn't, and it doesn't on my side, at least on a vanilla VS 2008 ASP.Net application. Perhaps you have explained this question wrong?
I have just tested this on my end, and it is working as expected.
string str = "{\"PCT51_URL\", \"MY\"}";
TextBox1.Text = str;// this is working fine to me.
But if it is still not working for you, you can replace those. e.g.
TextBox1.Text = str.Replace("\\","");
Note: I am using VS2010
I would like to do the following:
if (string.Contains("/"))
{
string.Replace("/", "\/"); //this isn't valid
}
I've tried
string.Replace("/", "\\/");
but this gives me what I started with. How can I do this?
Thanks
Strings are immutable, which means that any modification you do to a string results in a new one, you should assign the result of the Replace method:
if (myString.Contains("/"))
{
myString = myString.Replace("/", "\\/");
}
String.Replace returns the string with replacements made - it doesn't change the string itself. It can't; strings are immutable. You need something like:
text = text.Replace("/", "\\/");
(In future examples, it would be helpful if you could use valid variable names btw. It means that those wishing to respond with working code can use the same names as you've used.)
One way is to use a verbatim string literal
string.Replace("/", #"\");
Is there an easy way to create a multiline string literal in C#?
Here's what I have now:
string query = "SELECT foo, bar"
+ " FROM table"
+ " WHERE id = 42";
I know PHP has
<<<BLOCK
BLOCK;
Does C# have something similar?
You can use the # symbol in front of a string to form a verbatim string literal:
string query = #"SELECT foo, bar
FROM table
WHERE id = 42";
You also do not have to escape special characters when you use this method, except for double quotes as shown in Jon Skeet's answer.
It's called a verbatim string literal in C#, and it's just a matter of putting # before the literal. Not only does this allow multiple lines, but it also turns off escaping. So for example you can do:
string query = #"SELECT foo, bar
FROM table
WHERE name = 'a\b'";
This includes the line breaks (using whatever line break your source has them as) into the string, however. For SQL, that's not only harmless but probably improves the readability anywhere you see the string - but in other places it may not be required, in which case you'd either need to not use a multi-line verbatim string literal to start with, or remove them from the resulting string.
The only bit of escaping is that if you want a double quote, you have to add an extra double quote symbol:
string quote = #"Jon said, ""This will work,"" - and it did!";
As a side-note, with C# 6.0 you can now combine interpolated strings with the verbatim string literal:
string camlCondition = $#"
<Where>
<Contains>
<FieldRef Name='Resource'/>
<Value Type='Text'>{(string)parameter}</Value>
</Contains>
</Where>";
The problem with using string literal I find is that it can make your code look a bit "weird" because in order to not get spaces in the string itself, it has to be completely left aligned:
var someString = #"The
quick
brown
fox...";
Yuck.
So the solution I like to use, which keeps everything nicely aligned with the rest of your code is:
var someString = String.Join(
Environment.NewLine,
"The",
"quick",
"brown",
"fox...");
And of course, if you just want to logically split up lines of an SQL statement like you are and don't actually need a new line, you can always just substitute Environment.NewLine for " ".
One other gotcha to watch for is the use of string literals in string.Format. In that case you need to escape curly braces/brackets '{' and '}'.
// this would give a format exception
string.Format(#"<script> function test(x)
{ return x * {0} } </script>", aMagicValue)
// this contrived example would work
string.Format(#"<script> function test(x)
{{ return x * {0} }} </script>", aMagicValue)
Why do people keep confusing strings with string literals? The accepted answer is a great answer to a different question; not to this one.
I know this is an old topic, but I came here with possibly the same question as the OP, and it is frustrating to see how people keep misreading it. Or maybe I am misreading it, I don't know.
Roughly speaking, a string is a region of computer memory that, during the execution of a program, contains a sequence of bytes that can be mapped to text characters. A string literal, on the other hand, is a piece of source code, not yet compiled, that represents the value used to initialize a string later on, during the execution of the program in which it appears.
In C#, the statement...
string query = "SELECT foo, bar"
+ " FROM table"
+ " WHERE id = 42";
... does not produce a three-line string but a one liner; the concatenation of three strings (each initialized from a different literal) none of which contains a new-line modifier.
What the OP seems to be asking -at least what I would be asking with those words- is not how to introduce, in the compiled string, line breaks that mimick those found in the source code, but how to break up for clarity a long, single line of text in the source code without introducing breaks in the compiled string. And without requiring an extended execution time, spent joining the multiple substrings coming from the source code. Like the trailing backslashes within a multiline string literal in javascript or C++.
Suggesting the use of verbatim strings, nevermind StringBuilders, String.Joins or even nested functions with string reversals and what not, makes me think that people are not really understanding the question. Or maybe I do not understand it.
As far as I know, C# does not (at least in the paleolithic version I am still using, from the previous decade) have a feature to cleanly produce multiline string literals that can be resolved during compilation rather than execution.
Maybe current versions do support it, but I thought I'd share the difference I perceive between strings and string literals.
UPDATE:
(From MeowCat2012's comment) You can. The "+" approach by OP is the best. According to spec the optimization is guaranteed: http://stackoverflow.com/a/288802/9399618
Add multiple lines : use #
string query = #"SELECT foo, bar
FROM table
WHERE id = 42";
Add String Values to the middle : use $
string text ="beer";
string query = $"SELECT foo {text} bar ";
Multiple line string Add Values to the middle: use $#
string text ="Customer";
string query = $#"SELECT foo, bar
FROM {text}Table
WHERE id = 42";
You can use # and "".
string sourse = #"{
""items"":[
{
""itemId"":0,
""name"":""item0""
},
{
""itemId"":1,
""name"":""item1""
}
]
}";
In C# 11 [2022], you will be able to use Raw String literals.
The use of Raw String Literals makes it easier to use " characters without having to write escape sequences.
Solution for OP:
string query1 = """
SELECT foo, bar
FROM table
WHERE id = 42
""";
string query2 = """
SELECT foo, bar
FROM table
WHERE id = 42
and name = 'zoo'
and type = 'oversized "jumbo" grand'
""";
More details about Raw String Literals
See the Raw String Literals GitHub Issue for full details; and Blog article C# 11 Preview Updates – Raw string literals, UTF-8 and more!
I haven't seen this, so I will post it here (if you are interested in passing a string you can do this as well.) The idea is that you can break the string up on multiple lines and add your own content (also on multiple lines) in any way you wish. Here "tableName" can be passed into the string.
private string createTableQuery = "";
void createTable(string tableName)
{
createTableQuery = #"CREATE TABLE IF NOT EXISTS
["+ tableName + #"] (
[ID] INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
[Key] NVARCHAR(2048) NULL,
[Value] VARCHAR(2048) NULL
)";
}
Yes, you can split a string out onto multiple lines without introducing newlines into the actual string, but it aint pretty:
string s = $#"This string{
string.Empty} contains no newlines{
string.Empty} even though it is spread onto{
string.Empty} multiple lines.";
The trick is to introduce code that evaluates to empty, and that code may contain newlines without affecting the output. I adapted this approach from this answer to a similar question.
There is apparently some confusion as to what the question is, but there are two hints that what we want here is a string literal not containing any newline characters, whose definition spans multiple lines. (in the comments he says so, and "here's what I have" shows code that does not create a string with newlines in it)
This unit test shows the intent:
[TestMethod]
public void StringLiteralDoesNotContainSpaces()
{
string query = "hi"
+ "there";
Assert.AreEqual("hithere", query);
}
Change the above definition of query so that it is one string literal, instead of the concatenation of two string literals which may or may not be optimized into one by the compiler.
The C++ approach would be to end each line with a backslash, causing the newline character to be escaped and not appear in the output. Unfortunately, there is still then the issue that each line after the first must be left aligned in order to not add additional whitespace to the result.
There is only one option that does not rely on compiler optimizations that might not happen, which is to put your definition on one line. If you want to rely on compiler optimizations, the + you already have is great; you don't have to left-align the string, you don't get newlines in the result, and it's just one operation, no function calls, to expect optimization on.
If you don't want spaces/newlines, string addition seems to work:
var myString = String.Format(
"hello " +
"world" +
" i am {0}" +
" and I like {1}.",
animalType,
animalPreferenceType
);
// hello world i am a pony and I like other ponies.
You can run the above here if you like.
using System;
namespace Demo {
class Program {
static void Main(string[] args) {
string str = #"Welcome User,
Kindly wait for the image to
load";
Console.WriteLine(str);
}
}
}
Output
Welcome User,
Kindly wait for the image to
load