c# - string.Empty.StartsWith(((char)10781).ToString()) 总是返回 true？

Question

我试图处理以下字符:⨝ ( http://www.fileformat.info/info/unicode/char/2a1d/index.htm )

如果你检查一个以这个字符开头的空字符串，它总是返回true，这没有任何意义!这是为什么？

// visual studio 2008 hides lines that have this char literally (bug in visual studio?!?) so i wrote it's unicode instead.
char specialChar = (char)10781;
string specialString = specialChar.ToString();

// prints 1
Console.WriteLine(specialString.Length);

// prints 10781
Console.WriteLine((int)specialChar);

// prints false
Console.WriteLine(string.Empty.StartsWith("A"));

// both prints true WTF?!?
Console.WriteLine(string.Empty.StartsWith(specialString));
Console.WriteLine(string.Empty.StartsWith(((char)10781).ToString()));

Answer 1

您可以使用 ordinal StringComparison 修复此错误:

来自 MSDN 文档:

When you specify either StringComparison.Ordinal or StringComparison.OrdinalIgnoreCase, the string comparison will be non-linguistic. That is, the features that are specific to the natural language are ignored when making comparison decisions. This means the decisions are based on simple byte comparisons and ignore casing or equivalence tables that are parameterized by culture. As a result, by explicitly setting the parameter to either the StringComparison.Ordinal or StringComparison.OrdinalIgnoreCase, your code often gains speed, increases correctness, and becomes more reliable.

    char specialChar = (char)10781;


    string specialString = Convert.ToString(specialChar);

    // prints 1
    Console.WriteLine(specialString.Length);

    // prints 10781
    Console.WriteLine((int)specialChar);

    // prints false
    Console.WriteLine(string.Empty.StartsWith("A"));

    // prints false
    Console.WriteLine(string.Empty.StartsWith(specialString, StringComparison.Ordinal));