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{
public abstract int Compare (string x, string y);
public abstract bool Equals (string x, string y);
public abstract int GetHashCode (string obj);
public static StringComparer Create (CultureInfo culture,
bool ignoreCase);
public static StringComparer CurrentCulture { get; }
public static StringComparer CurrentCultureIgnoreCase { get; }
public static StringComparer InvariantCulture { get; }
public static StringComparer InvariantCultureIgnoreCase { get; }
public static StringComparer Ordinal { get; }
public static StringComparer OrdinalIgnoreCase { get; }
}
Because StringComparer is abstract, you obtain instances via its static methods and
properties. StringComparer.Ordinal mirrors the default behavior for string equality
comparison and StringComparer.CurrentCulture for order comparison.
In the following example, an ordinal case-insensitive dictionary is created, such that
dict["Joe"] and dict["JOE"] mean the same thing:
var dict = new Dictionary (StringComparer.OrdinalIgnoreCase);
In the next example, an array of names is sorted, using Australian English:
string[] names = { "Tom", "HARRY", "sheila" };
CultureInfo ci = new CultureInfo ("en-AU");
Array.Sort (names, StringComparer.Create (ci, false));
The final example is a culture-aware version of the SurnameComparer we wrote in the
previous section (to compare names suitable for a phonebook listing):
class SurnameComparer : Comparer
{
StringComparer strCmp;
public SurnameComparer (CultureInfo ci)
{
// Create a case-sensitive, culture-sensitive string comparer
strCmp = StringComparer.Create (ci, false);
}
string Normalize (string s)
{
s = s.Trim();
if (s.ToUpper().StartsWith ("MC")) s = "MAC" + s.Substring (2);
return s;
}
public override int Compare (string x, string y)
{
// Directly call Compare on our culture-aware StringComparer
return strCmp.Compare (Normalize (x), Normalize (y));
}
}
Plugging in Equality and Order | 309
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