Some while ago I developed a Settings system, where the SettingValue type should be checked. The DateTime.TryParse function did not do all the work I wanted it to do, so I thought ‘why not develop my own workaround’ ? It is posted below…

/// <summary>
/// The IsDateTime function returns whether the given expression is a DateTime or not.
/// </summary>
/// <param name="expression">Expression to check for being DateTime.</param>
/// <returns>Boolean</returns>
/// <remarks>
/// The DateTime expression can be given as ticks or as normal DateTime representation.
/// </remarks>
public static bool IsDateTime(object expression) {
if(expression == null) return false;Bert Loedeman

string stringExpression = System.Convert.ToString(expression);
if(String.IsNullOrEmpty(stringExpression)) return false;

// DateTime can be specified in ticks. In that case the string should be convertible
// to a long (System.Int64) and fit in a specific range.
long retLong;
if(Int64.TryParse(stringExpression, out retLong)) {
// Ticks: 0 = DateTime.MinValue, 0x2bca2875f4373fff = DateTime.MaxValue
if((retLong < DateTime.MinValue.Ticks) || (retLong > DateTime.MaxValue.Ticks)) return false;
return true;
}

DateTime retDateTime;
return DateTime.TryParse(stringExpression, out retDateTime);
}