代码:

string someString1 = "\tHello\r\n\tWorld!\r\n";
string someString2 = @"\tHello\r\n\tWorld!\r\n";

Console.WriteLine(someString1);
Console.WriteLine(someString2);

输出:

    Hello
    World!

\tHello\r\n\tWorld!\r\n

Hallgrim的回答很好，但是“+”，换行和缩进的添加破坏了我的功能。一个简单的解决方法是:

private static string ToLiteral(string input)
{
    using (var writer = new StringWriter())
    {
        using (var provider = CodeDomProvider.CreateProvider("CSharp"))
        {
            provider.GenerateCodeFromExpression(new CodePrimitiveExpression(input), writer, new CodeGeneratorOptions {IndentString = "\t"});
            var literal = writer.ToString();
            literal = literal.Replace(string.Format("\" +{0}\t\"", Environment.NewLine), "");
            return literal;
        }
    }
}

这是一个完全可行的实现，包括Unicode和ASCII不可打印字符的转义。它没有像Hallgrim的答案那样插入“+”符号。

static string ToLiteral(string input) {
    StringBuilder literal = new StringBuilder(input.Length + 2);
    literal.Append("\"");
    foreach (var c in input) {
        switch (c) {
            case '\"': literal.Append("\\\""); break;
            case '\\': literal.Append(@"\\"); break;
            case '\0': literal.Append(@"\0"); break;
            case '\a': literal.Append(@"\a"); break;
            case '\b': literal.Append(@"\b"); break;
            case '\f': literal.Append(@"\f"); break;
            case '\n': literal.Append(@"\n"); break;
            case '\r': literal.Append(@"\r"); break;
            case '\t': literal.Append(@"\t"); break;
            case '\v': literal.Append(@"\v"); break;
            default:
                // ASCII printable character
                if (c >= 0x20 && c <= 0x7e) {
                    literal.Append(c);
                // As UTF16 escaped character
                } else {
                    literal.Append(@"\u");
                    literal.Append(((int)c).ToString("x4"));
                }
                break;
        }
    }
    literal.Append("\"");
    return literal.ToString();
}

注意，这也转义了所有Unicode字符。如果你的环境支持它们，你可以改变这一部分，只转义控制字符:

// UTF16 control characters
} else if (Char.GetUnicodeCategory(c) == UnicodeCategory.Control) {
    literal.Append(@"\u");
    literal.Append(((int)c).ToString("x4"));
} else {
    literal.Append(c);
}

我提交了自己的实现，它处理空值，并且由于使用数组查找表、手动十六进制转换和避免开关语句，因此性能应该更好。

using System;
using System.Text;
using System.Linq;

public static class StringLiteralEncoding {
  private static readonly char[] HEX_DIGIT_LOWER = "0123456789abcdef".ToCharArray();
  private static readonly char[] LITERALENCODE_ESCAPE_CHARS;

  static StringLiteralEncoding() {
    // Per http://msdn.microsoft.com/en-us/library/h21280bw.aspx
    var escapes = new string[] { "\aa", "\bb", "\ff", "\nn", "\rr", "\tt", "\vv", "\"\"", "\\\\", "??", "\00" };
    LITERALENCODE_ESCAPE_CHARS = new char[escapes.Max(e => e[0]) + 1];
    foreach(var escape in escapes)
      LITERALENCODE_ESCAPE_CHARS[escape[0]] = escape[1];
  }

  /// <summary>
  /// Convert the string to the equivalent C# string literal, enclosing the string in double quotes and inserting
  /// escape sequences as necessary.
  /// </summary>
  /// <param name="s">The string to be converted to a C# string literal.</param>
  /// <returns><paramref name="s"/> represented as a C# string literal.</returns>
  public static string Encode(string s) {
    if(null == s) return "null";

    var sb = new StringBuilder(s.Length + 2).Append('"');
    for(var rp = 0; rp < s.Length; rp++) {
      var c = s[rp];
      if(c < LITERALENCODE_ESCAPE_CHARS.Length && '\0' != LITERALENCODE_ESCAPE_CHARS[c])
        sb.Append('\\').Append(LITERALENCODE_ESCAPE_CHARS[c]);
      else if('~' >= c && c >= ' ')
        sb.Append(c);
      else
        sb.Append(@"\x")
          .Append(HEX_DIGIT_LOWER[c >> 12 & 0x0F])
          .Append(HEX_DIGIT_LOWER[c >>  8 & 0x0F])
          .Append(HEX_DIGIT_LOWER[c >>  4 & 0x0F])
          .Append(HEX_DIGIT_LOWER[c       & 0x0F]);
    }

    return sb.Append('"').ToString();
  }
}

很久以前，我发现了这个:

private static string ToLiteral(string input)
{
    using (var writer = new StringWriter())
    {
        using (var provider = CodeDomProvider.CreateProvider("CSharp"))
        {
            provider.GenerateCodeFromExpression(new CodePrimitiveExpression(input), writer, null);
            return writer.ToString();
        }
    }
}

这段代码:

var input = "\tHello\r\n\tWorld!";
Console.WriteLine(input);
Console.WriteLine(ToLiteral(input));

生产:

    Hello
    World!
"\tHello\r\n\tWorld!"

最近，Graham发现你可以在NuGet上使用Roslyn的Microsoft.CodeAnalysis.CSharp包:

private static string ToLiteral(string valueTextForCompiler)
{
    return Microsoft.CodeAnalysis.CSharp.SymbolDisplay.FormatLiteral(valueTextForCompiler, false);
}

如果JSON约定对于你想要转义的未转义字符串足够，并且你已经使用了JSON。NET (Newtonsoft.Json)在你的项目中(它有一个相当大的开销)，你可以像下面这样使用这个包:

using System;
using Newtonsoft.Json;

public class Program
{
    public static void Main()
    {
        Console.WriteLine(ToLiteral(@"abc\n123"));
    }

    private static string ToLiteral(string input)
    {
        return JsonConvert.DeserializeObject<string>("\"" + input + "\"");
    }
}