String Comparison And Alphabetic Order of Individual Characters

Alexandar picture Alexandar · Feb 19, 2013 · Viewed 25.4k times · Source

I have a question related to string comparison vs. character comparison.

Characters > and 0 (zero) have following decimal values 62 and 48 accordingly.

When I compare two characters in the following code, I get value True (which is correct)

Console.WriteLine('>' > '0');

When I compare two one-character strings in the following code, I get value -1 which indicates that ">" is less than "0" (default culture is English)

Console.WriteLine(string.Compare(">", "0"));

Whereas comparison of "3" and "1" (51 and 49 code values) in the following code returns 1 (as expected)

Console.WriteLine(string.Compare("3", "1"));

Also, string.Compare(string str1, string str2) documentation says:

The comparison uses the current culture to obtain culture-specific information such as casing rules and the alphabetic order of individual characters

Would you be able to explain (or provide reference to some documentation) how string comparison is implemented e.g. how alphabetic order of individual characters is calculated etc?

Answer

dtb picture dtb · Feb 19, 2013

The sort order of strings depends on the culture you use.

StringComparer.CurrentCulture sorts the following 1-character strings as follows on my machine:

' -   ! " # $ % & (  ) * , . / : ; ? @ [
\ ] ^ _ ` { | } ~ +  < = > 0 1 2 3 4 5 6
7 8 9 a A b B c C d  D e E f F g G h H i
I j J k K l L m M n  N o O p P q Q r R s
S t T u U v V w W x  X y Y z Z

StringComparer.Ordinal sorts the same strings as follows:

  ! " # $ % & ' ( )  * + , - . / 0 1 2 3
4 5 6 7 8 9 : ; < =  > ? @ A B C D E F G
H I J K L M N O P Q  R S T U V W X Y Z [
\ ] ^ _ ` a b c d e  f g h i j k l m n o
p q r s t u v w x y  z { | } ~