c# - 排序的特殊性

Question

字符代码'-'是45，字符代码'a'是 97。很明显 '-' < 'a'是真的。

Console.WriteLine((int)'-' + " " + (int)'a');
Console.WriteLine('-' < 'a');

45 97
True

因此下面排序的结果是正确的

var a1 = new string[] { "a", "-" };
Console.WriteLine(string.Join(" ", a1));
Array.Sort(a1);
Console.WriteLine(string.Join(" ", a1));

a -
- a

但是为什么下面排序的结果是错误的呢？

var a2 = new string[] { "ab", "-b" };
Console.WriteLine(string.Join(" ", a2));
Array.Sort(a2);
Console.WriteLine(string.Join(" ", a2));

ab -b
ab -b

Answer 1

- 被忽略，

so - = "" < a
and -b = "b" > "ab"

这是因为文化排序(默认)

https://msdn.microsoft.com/en-us/library/system.globalization.compareoptions(v=vs.110).aspx

The .NET Framework uses three distinct ways of sorting: word sort, string  

sort, and ordinal sort. Word sort performs a culture-sensitive comparison of strings. Certain nonalphanumeric characters might have special weights assigned to them. For example, the hyphen ("-") might have a very small weight assigned to it so that "coop" and "co-op" appear next to each other in a sorted list. String sort is similar to word sort, except that there are no special cases. Therefore, all nonalphanumeric symbols come before all alphanumeric characters. Ordinal sort compares strings based on the Unicode values of each element of the string.