C#

Blake Miller wrote:

Under what conditions might the relative speed vary?

• strings are reference-types, and atomic in memory
  
• Converting them both before the comparison is slower than comparing them directly (there can be only one!)
  
• Microsoft "advises" to use uppercase constants. Has something to do with efficiency in comparing.
  
• Does it matter?
  

Many string operations, most important the Compare and Equals methods, now provide an overload that accepts a StringComparision enumeration value as a parameter.

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.

Bastard Programmer from Hell
if you can't read my code, try converting it here[^]

Blake Miller wrote:

It does matter. I am looking into this because customers are complaining about
CPU load.

int ITERATIONS = 1000000;

string s1 = "Hello World";
string s2 = "hello world";

Debug.Assert(s1.ToLower() == s2.ToLower());
Debug.Assert(string.Compare(s1, s2, true) == 0);

var sw1 = new Stopwatch();
sw1.Start();
for (int i = 0; i < ITERATIONS; i++)
{
   Debug.Assert(s1.ToLower() == s2.ToLower());
}
sw1.Stop();

var sw2 = new Stopwatch();
sw2.Start();
for (int i = 0; i < ITERATIONS; i++)
{
   Debug.Assert(string.Compare(s1, s2, true) == 0);
}
sw2.Stop();


Console.WriteLine("ToLower: {0}", sw1.Elapsed);
Console.WriteLine("Compare: {0}", sw2.Elapsed);

ToLower: 00:00:00.4507542
Compare: 00:00:00.1856049

TheGermoz wrote:

has anyone experience of a working solution?

Bastard Programmer from Hell
if you can't read my code, try converting it here[^]

TheGermoz wrote:

I was looking for a ready to run solution to do not reinvent the wheel

Bastard Programmer from Hell
If you can't read my code, try converting it here[^]
They hate us for our freedom![^]