C#值类型、引用类型中的Equals和==的区别浅析

            {
                throw new ArgumentException(Environment.GetResourceString("NotSupported_StringComparison"), "comparisonType");
            }
            if (a == b)
            {
                return true;
            }
            if (a == null || b == null)
            {
                return false;
            }
            switch (comparisonType)
            {
            case StringComparison.CurrentCulture:
                return CultureInfo.CurrentCulture.CompareInfo.Compare(a, b, CompareOptions.None) == 0;
            case StringComparison.CurrentCultureIgnoreCase:
                return CultureInfo.CurrentCulture.CompareInfo.Compare(a, b, CompareOptions.IgnoreCase) == 0;
            case StringComparison.InvariantCulture:
                return CultureInfo.InvariantCulture.CompareInfo.Compare(a, b, CompareOptions.None) == 0;
            case StringComparison.InvariantCultureIgnoreCase:
                return CultureInfo.InvariantCulture.CompareInfo.Compare(a, b, CompareOptions.IgnoreCase) == 0;
            case StringComparison.Ordinal:
                return a.Length == b.Length && string.EqualsHelper(a, b);
            case StringComparison.OrdinalIgnoreCase:
                if (a.Length != b.Length)
                {