如何删除无法识别的转义序列的错误 [英] How can remove the error coming unrecognized escape sequence

问题描述

 SqlConnection con =  new  SqlConnection（ConfigurationManager.ConnectionStrings [  Data Source = .\SQLEXPRESS; AttachDbFilename = | DataDirectory | \Database.mdf; Integrated Security = True; User Instance = True]。ConnectionString）; 

我的尝试：



< pre lang =c＃> SqlConnection con = new SqlConnection（ConfigurationManager.ConnectionStrings [ Data Source = .\\SQLEXPRESS; AttachDbFilename = | DataDirectory | \\Database.mdf; Integrated Security = True; User Instance = True]。ConnectionString）;

解决方案

在C＃字符串中，反斜杠字符是一个特殊字符，它引入了转义序列，如双引号，换行符等。如果你想在字符串中使用反斜杠字符，有两种方法。

1）使用反斜杠的转义序列：'\\'：

< pre lang =c＃> string str = D ：\\Temp \\;

2）在字符串前加上atsign，关闭转义序列：

  string  str =  @  D：\Temp \; 

在第二种情况下，要插入双引号字符，请使用两个双引号：

< pre lang =c＃> string str = @ John说Hello;

'\ S'不是可识别的转义序列，因此您收到此错误消息。



但是......正如NotPoliticallyCorrect所说：你为什么要读书使用连接字符串从配置文件中获取连接字符串？

通常，您将使用：

  using （SqlConnection con =  new  SqlConnection（ConfigurationManager.ConnectionStrings [ < span class =code-string> MyDB]。ConnectionString））
 {
 ... 
} 

SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;User Instance=True"].ConnectionString);

What I have tried:

SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["Data Source=.\\SQLEXPRESS;AttachDbFilename=|DataDirectory|\\Database.mdf;Integrated Security=True;User Instance=True"].ConnectionString);

解决方案

In C# strings, the backslash character is a "special" which introduces "escape sequences" like double quotes, newline, and so forth. If you want to use a backslash character in a string, there are two ways.
1) Use the escape sequence for backslash: '\\':

string str = "D:\\Temp\\";

2) Preface the string with an atsign, which turns off escape sequences:

string str = @"D:\Temp\";

In the second case, to insert a doublke quote character you use two doublequotes:

string str = @"John said ""Hello""";

'\S' is not a recognised escape sequence, so you get this error message.

But ... as NotPoliticallyCorrect says: "why are you trying to read a connection string from your config file by using a connection string?"
Normally, you would use:

using (SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["MyDB"].ConnectionString))
   {
   ...
   }

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