string.Replace does not work for quote

((string)dt.Rows[i][1]).Replace("'", "\\'")
开发者_高级运维

I want the result that if any string have quote it change it into slash quote, e.g. John's -> John\'s

but the above replace function is not working fine. it results like John\\'s

but if we change the code to

((string)dt.Rows[i][1]).Replace("'", "\'")

it gives the Result like John's

does change it anyway.

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Because the backslash is the escape character, you need to tell it you want to treat it like a literal string. You do this by prepending an @ to the string:

((string)dt.Rows[i][1]).Replace("'", @"\'") 

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Try a double backslash.

\\

Just one backslash is an escape; two is an actual backslash.

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Use "\\'" or @"\'" for the replacement string. The backslash is the escape character in C# string literals. See the explanation of string literals in C#: \' in a string literal results in just a single quote. The reason this escape sequence exists, is because single quotes would require escaping if you were using a char literal ('\'').

The @ indicates that you're using verbatim string syntax, which allows for multi-line strings and eliminates the need to escape characters, apart from double quote, which you would escape with double double quotes (Visual Basic style).

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Can you clarify please? Are you saying that

((string)dt.Rows[i][1]).Replace("'", "\\'") 

does not replace a ' with \' ?

Because I just tried it and it works fine. I.e. this

            string one = "blah'";
            string two = one.Replace("'", "\\'");

            Console.WriteLine(two);

Prints blah\'

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Replace("'", "\'") use double slash

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You could use something like this:

private static string replace(String input)
{
   return Regex.Replace(input, "('|\")", "\\'");
}

static void Main(string[] args)
{
   String value1 = "John Steve's";
   String value2 = "John Steve\"s";

   Console.WriteLine(replace(value1));
   Console.WriteLine(replace(value2));
 }

Results:

John Steve\'s

John Steve\'s

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If you want to prepare an SQL query, I think the best method is to replace a single ' for ''. For instance, if you wanto to search John O'Connor, this would work (at least in SQL Server, Access, Oracle, ...).

select ... from users where username = 'Jonh O''Connor'