Sort a char array case-insensitively

[Paul E Collins]

char[] c = { 'a', 'b', 'c', 'A', 'B', 'C' };
Array.Sort(c, CaseInsensitiveComparer.Default);

After this, c is ordered { 'A', 'B', 'C', 'a', 'b', 'c' }.

I want letters to be sorted together regardless of case, e.g. 'A' next to
'a'.

Why doesn't that case-insensitive sort work? What should I do instead?

Eq.

[Jeroen Mostert]

Paul E Collins wrote:

char[] c = { 'a', 'b', 'c', 'A', 'B', 'C' };
Array.Sort(c, CaseInsensitiveComparer.Default);

After this, c is ordered { 'A', 'B', 'C', 'a', 'b', 'c' }.

I want letters to be sorted together regardless of case, e.g. 'A' next to
'a'.

Why doesn't that case-insensitive sort work? What should I do instead?

CaseInsensitiveComparer operates on strings only, not characters. I don't
think the framework has lexicographical comparers for characters out of the box.

The most straightforward way to achieve what you want is to use a
Comparison<Tthat lifts its arguments to strings:

Array.Sort(c, (a, b) =string.Compare(a.ToString(), b.ToString(),
StringComparison.CurrentCultureIgnoreCase));

There may be a more elegant way.

--
J.

[=?ISO-8859-1?Q?G=F6ran_Andersson?=]

Paul E Collins wrote:

char[] c = { 'a', 'b', 'c', 'A', 'B', 'C' };
Array.Sort(c, CaseInsensitiveComparer.Default);

After this, c is ordered { 'A', 'B', 'C', 'a', 'b', 'c' }.

I want letters to be sorted together regardless of case, e.g. 'A' next to
'a'.

Why doesn't that case-insensitive sort work?

Because the CaseInsensetiveComparer compares strings, and if you use it
to compare something different, it will fallback to using
Comparer.Default.Compare() instead.

What should I do instead?

You can make your own comparer that turns the characters to lower case
and compares them:

Array.Sort(c, (x, y) =char.ToLower(x) - char.ToLower(y));

or

Array.Sort(c, delegate(char x, char y) { return char.ToLower(x) -
char.ToLower(y); });

--
Göran Andersson
_____
http://www.guffa.com