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copied!<p>Don't reinvent wheels, use the <a href="http://msdn.microsoft.com/en-us/library/system.datetime.tryparseexact.aspx" rel="nofollow"><code>DateTime.TryParseExact</code></a> method which is built specifically for this purpose. Forget about regexes and substrings when you are dealing with dates in the .NET framework:</p> <pre><code>public static bool CheckDate(string number, out DateTime date) { return DateTime.TryParseExact(number, "dd/MM/yyyy", CultureInfo.InvariantCulture, DateTimeStyles.None, out date); } </code></pre> <p>And now as you can see defining the <code>CheckDate</code> becomes kinda meaningless because it already exists in the BCL. You would simply use it like this:</p> <pre><code>string number = "that's your number coming from somewhere which should be a date"; DateTime date; if (DateTime.TryParseExact( number, "dd/MM/yyyy", CultureInfo.InvariantCulture, DateTimeStyles.None, out date )) { // the number was in the correct format // => you could use the days, months, from the date variable which is now a DateTime string dd = date.Day.ToString(); string mm = date.Month.ToString(); string yyyy = date.Year.ToString(); // do whatever you intended to do with those 3 variables before } else { // tell the user to enter a correct date in the format dd/MM/yyyy } </code></pre> <hr> <p>UPDATE: </p> <p>Since I got a remark in the comments section that I am not actually answering the question, you could use a similar approach to the one I recommend. But please, promise me you will <strong>never write a code like this</strong>, it's just for illustration of the TryXXX pattern.</p> <p>define a model:</p> <pre><code>public class Patterns { public string DD { get; set; } public string MM { get; set; } public string YYYY { get; set; } } </code></pre> <p>and then modify your CheckDate method so that it sends an out parameter:</p> <pre><code>public static bool CheckDate(string number, out Patterns patterns) { patterns = null; string new_number = number.ToString(); if (new_number.Length == 8) { Patterns = new Patterns { YYYY = new_number.Substring(0, 4), MM = new_number.Substring(4, 2), DD = new_number.Substring(6, 2) } return true; } else { return false; } } </code></pre> <p>which you could use like this:</p> <pre><code>string number = "that's your number coming from somewhere which should be a date"; Patterns patterns; if (CheckDate(numbers, out patterns) { string dd = patterns.DD; string mm = patterns.MM; string yyyy = patterns.YYYY; // do whatever you intended to do with those 3 variables before } else { // tell the user to enter a correct date in the format dd/MM/yyyy } </code></pre>

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