I will explain my problem(excuse my bad English), I have a .NET exe in which every milliseconds of processing is very important.
This program does lots of string co
This is a known issue in .NET 4.
Here is the MS Connect report.
Ok i have a response of one of my question.
With reflector i can see the difference between framework 2 and 4 and that explain my perforamnce issue.
public int IndexOf(string value, int startIndex, int count, StringComparison comparisonType)
{
if (value == null)
{
throw new ArgumentNullException("value");
}
if ((startIndex < 0) || (startIndex > this.Length))
{
throw new ArgumentOutOfRangeException("startIndex", Environment.GetResourceString("ArgumentOutOfRange_Index"));
}
if ((count < 0) || (startIndex > (this.Length - count)))
{
throw new ArgumentOutOfRangeException("count", Environment.GetResourceString("ArgumentOutOfRange_Count"));
}
switch (comparisonType)
{
case StringComparison.CurrentCulture:
return CultureInfo.CurrentCulture.CompareInfo.IndexOf(this, value, startIndex, count, CompareOptions.None);
case StringComparison.CurrentCultureIgnoreCase:
return CultureInfo.CurrentCulture.CompareInfo.IndexOf(this, value, startIndex, count, CompareOptions.IgnoreCase);
case StringComparison.InvariantCulture:
return CultureInfo.InvariantCulture.CompareInfo.IndexOf(this, value, startIndex, count, CompareOptions.None);
case StringComparison.InvariantCultureIgnoreCase:
return CultureInfo.InvariantCulture.CompareInfo.IndexOf(this, value, startIndex, count, CompareOptions.IgnoreCase);
case StringComparison.Ordinal:
return CultureInfo.InvariantCulture.CompareInfo.IndexOf(this, value, startIndex, count, CompareOptions.Ordinal);
case StringComparison.OrdinalIgnoreCase:
return TextInfo.IndexOfStringOrdinalIgnoreCase(this, value, startIndex, count);
}
throw new ArgumentException(Environment.GetResourceString("NotSupported_StringComparison"), "comparisonType");
}
This is the base code of function IndexOf of the 2 framework (no difference between 4 and 2)
But in the function TextInfo.IndexOfStringOrdinalIgnoreCase there are differences :
Framework 2 :
internal static unsafe int IndexOfStringOrdinalIgnoreCase(string source, string value, int startIndex, int count)
{
if (source == null)
{
throw new ArgumentNullException("source");
}
return nativeIndexOfStringOrdinalIgnoreCase(InvariantNativeTextInfo, source, value, startIndex, count);
}
Framework 4 :
internal static int IndexOfStringOrdinalIgnoreCase(string source, string value, int startIndex, int count)
{
if ((source.Length == 0) && (value.Length == 0))
{
return 0;
}
int num = startIndex + count;
int num2 = num - value.Length;
while (startIndex <= num2)
{
if (CompareOrdinalIgnoreCaseEx(source, startIndex, value, 0, value.Length, value.Length) == 0)
{
return startIndex;
}
startIndex++;
}
return -1;
}
The main algorithm has changed in framework 2 the call is a nativeDll that has been removed of framework 4. Its good to know
I cannot answer on your specific .NET 4 speed issue.
However you'd probably gain much more speed by improving your algo. Check out the Rabin-Karp string search algo.