public int IndexOf(string value, int startIndex, int count, StringComparison comparisonType)
{
// Parameter checking will be done by CompareInfo.IndexOf.
switch (comparisonType)
{
case StringComparison.CurrentCulture:
case StringComparison.CurrentCultureIgnoreCase:
return(CultureInfo.CurrentCulture.CompareInfo.IndexOf(this, value, startIndex, count, GetCaseCompareOfComparisonCulture(comparisonType)));
case StringComparison.InvariantCulture:
case StringComparison.InvariantCultureIgnoreCase:
return(CompareInfo.Invariant.IndexOf(this, value, startIndex, count, GetCaseCompareOfComparisonCulture(comparisonType)));
case StringComparison.Ordinal:
case StringComparison.OrdinalIgnoreCase:
return(Ordinal.IndexOf(this, value, startIndex, count, comparisonType == StringComparison.OrdinalIgnoreCase));
default:
throw (value is null)
? new ArgumentNullException(nameof(value))
: new ArgumentException(SR.NotSupported_StringComparison, nameof(comparisonType));
}
}