How to get the Indexof backslash(\) in C#?

Question

is there way to find out the indexof backslash in string variable?

i have string

var str = "      \"AAP, FB, VOD, ART, BAG, CAT, DDL\"\n    "

int stIdx = str.indexof('\"') // output as 6

int edIdx = str.indexof('\', stIdx+1); // output as -1

output i'm looking for is as below

AAP, FB, VOD, ART, BAG, CAT, DDL

I would suggest that you have to escape the character i.e. you have to use `'\\'` (double backslash) in this particular case — Jaood_xD, Sep 01 '22 at 13:23
I think your string represents a `UTF-16` string. In that case the `\n` represents a single character for a new line. Thus searching for the character \ won't be able to find it as that is a different character than a new line. — NotFound, Sep 01 '22 at 13:26
Does this answer your question? [How do I write a backslash (\‌) in a string?](https://stackoverflow.com/questions/18532691/how-do-i-write-a-backslash-in-a-string) — Charlieface, Sep 01 '22 at 13:27
```\n``` in your string gets replaced as a single newline character and therefor there is no ```\``` character in the string. — phuzi, Sep 01 '22 at 13:28
Note that the code you've written doesn't have any output, as it doesn't compile, for multiple reasons. This is why it's always important to provide a [mcve] rather than pseudo-code. — Jon Skeet, Sep 01 '22 at 13:30

Natlink · Answer 1 · 2022-09-01T13:30:53.260

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You need to escape your backslash to use it as a char value.

Cause backslash is a special character, '\' didn't refer to backslash as a character, but as an instruction which let you escape any character.

int index = str.IndexOf('\\'); //should give you the right answer

edited Sep 01 '22 at 13:30

answered Sep 01 '22 at 13:25

Natlink

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That code won't compile - you mean `IndexOf` rather than `indexof`. – Jon Skeet Sep 01 '22 at 13:28
I just reused the syntaxe used by the person who asked the question. But actually yes, it's indexOf, i edit. – Natlink Sep 01 '22 at 13:29
No, it's not `indexOf`, it's `IndexOf`. – Jon Skeet Sep 01 '22 at 13:29

score 0 · Answer 2 · answered Sep 01 '22 at 13:35

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The character sequence '\n' is used for a newline.

string str = "Hi\n";

In the above example str consists of the characters 'H', 'i', and a newline character. There is no '\' character.

Try the following:

int edIdx = str.indexof('\n', stIdx+1);

answered Sep 01 '22 at 13:35

Jonathan Dodds

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score 0 · Accepted Answer · answered Sep 02 '22 at 11:42

A \" in a string is not a backslash followed by a quote, but just a quote. The backslash in the string literal escapes the quote: it should be just a character, not the end of the string constant.
The \n is not an escaped 'n' (it wouldn't need escaping) but a (single) newline character.

Your string literal doesn't really contain any backslashes.

Your code, with typos fixed:

var str = "      \"AAP, FB, VOD, ART, BAG, CAT, DDL\"\n    ";

int stIdx = str.IndexOf('"')+1; // output as 7 - you don't want position of " but 'A'

int edIdx = str.IndexOf('"', stIdx); // output as 39

Console.WriteLine($"from {stIdx} to {edIdx}"); // "from 7 to 39"
Console.WriteLine(str.Substring(stIdx, edIdx-stIdx)); // "AAP, FB, VOD, ART, BAG, CAT, DDL"

In a character literal (delimited by single quotes), you do not need to escape the double quote, so '"' works fine. Although it is no problem if you do escape it: '\"' - which is still a single " character.

How to get the Indexof backslash(\) in C#?

3 Answers3