Data Validation with Regular Expressions in C#

Here is some C# functions that validate Numbers, Email and Alpha numeric values

Note : using System.Text.RegularExpressions;

public static bool IsNumber(String strNumber)
        {
            Regex objNotNumberPattern = new Regex("[^0-9.-]");
            Regex objTwoDotPattern = new Regex("[0-9]*[.][0-9]*[.][0-9]*");
            Regex objTwoMinusPattern = new Regex("[0-9]*[-][0-9]*[-][0-9]*");
            String strValidRealPattern = "^([-]|[.]|[-.]|[0-9])[0-9]*[.]*[0-9]+$";
            String strValidIntegerPattern = "^([-]|[0-9])[0-9]*$";
            Regex objNumberPattern = new Regex("(" + strValidRealPattern + ")|(" + strValidIntegerPattern + ")");
            return !objNotNumberPattern.IsMatch(strNumber) &&
            !objTwoDotPattern.IsMatch(strNumber) &&
            !objTwoMinusPattern.IsMatch(strNumber) &&
            objNumberPattern.IsMatch(strNumber);
        }
        // Function to Test for Positive Number both Integer & Real 
        public static bool IsPositiveNumber(String strNumber)
        {
            Regex objNotPositivePattern = new Regex("[^0-9.]");
            Regex objPositivePattern = new Regex("^[.][0-9]+$|[0-9]*[.]*[0-9]+$");
            Regex objTwoDotPattern = new Regex("[0-9]*[.][0-9]*[.][0-9]*");
            return !objNotPositivePattern.IsMatch(strNumber) &&
            objPositivePattern.IsMatch(strNumber) &&
            !objTwoDotPattern.IsMatch(strNumber);
        }
        
        // Function to test for Positive Integers. 
        public static bool IsNaturalNumber(String strNumber)
        {
            Regex objNotNaturalPattern = new Regex("[^0-9]");
            Regex objNaturalPattern = new Regex("0*[1-9][0-9]*");
            return !objNotNaturalPattern.IsMatch(strNumber) &&
            objNaturalPattern.IsMatch(strNumber);
        }
        // Function to test for Positive Integers with zero inclusive 
        public static bool IsWholeNumber(String strNumber)
        {
            Regex objNotWholePattern = new Regex("[^0-9]");
            return !objNotWholePattern.IsMatch(strNumber);
        }
        // Function to Test for Integers both Positive & Negative 
        public static bool IsInteger(String strNumber)
        {
            Regex objNotIntPattern = new Regex("[^0-9-]");
            Regex objIntPattern = new Regex("^-[0-9]+$|^[0-9]+$");
            return !objNotIntPattern.IsMatch(strNumber) && objIntPattern.IsMatch(strNumber);
        }
        // Function To test for Alphabets. 
        public static bool IsAlpha(String strToCheck)
        {
            Regex objAlphaPattern = new Regex("[^a-zA-Z]");
            return !objAlphaPattern.IsMatch(strToCheck);
        }
        // Function to Check for AlphaNumeric.
        public static bool IsAlphaNumeric(String strToCheck)
        {
            Regex objAlphaNumericPattern = new Regex("[^a-zA-Z0-9]");
            return !objAlphaNumericPattern.IsMatch(strToCheck);
        }

 public static bool IsEmail(string strEmail)
        {
            string patternStrict = @"^(([^<>()[\]\\.,;:\s@\""]+"
                       + @"(\.[^<>()[\]\\.,;:\s@\""]+)*)|(\"".+\""))@"
                       + @"((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}"
                       + @"\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+"
                       + @"[a-zA-Z]{2,}))$";
            Regex emailregex = new Regex(patternStrict);
                      
            Match m = emailregex.Match(strEmail);
            if (m.Success)
                return true;
            else
                return false;

        }