public int IndexOf(String value, int startIndex, int count, StringComparison comparisonType)
{
// Validate inputs
if (value == null)
{
throw new ArgumentNullException(nameof(value));
}
if (startIndex < 0 || startIndex > this.Length)
{
throw new ArgumentOutOfRangeException(nameof(startIndex), SR.ArgumentOutOfRange_Index);
}
if (count < 0 || startIndex > this.Length - count)
{
throw new ArgumentOutOfRangeException(nameof(count), SR.ArgumentOutOfRange_Count);
}
switch (comparisonType)
{
case StringComparison.CurrentCulture:
return(FormatProvider.IndexOf(this, value, startIndex, count));
case StringComparison.CurrentCultureIgnoreCase:
return(FormatProvider.IndexOfIgnoreCase(this, value, startIndex, count));
case StringComparison.Ordinal:
return(FormatProvider.OrdinalIndexOf(this, value, startIndex, count));
case StringComparison.OrdinalIgnoreCase:
return(FormatProvider.OrdinalIndexOfIgnoreCase(this, value, startIndex, count));
default:
throw new ArgumentException(SR.NotSupported_StringComparison, nameof(comparisonType));
}
}