Question

I know I can use [Required], [StringLength] annotations for validating empty string and length requirements but would like to use same regular expression for validating them as well. I haven’t tried as I am not very good on regex.

Regular Expression should validate

1.Empty string (should not be allowed)

2.Length of characters (8)

3.Integer

4.Starting number (should be 1)

Here is the code:

 [DisplayName("Account Number:")]
 [RegularExpression("", 
             ErrorMessage = "An eight digit long number starting with 1 required")]
 public string accountNo { get; set; }

Thanks in advance !

Answer 1

Use this regular expression ^1\d{7}$

or

^1[0-9]{7}$

or, in a crunch,

  ^1[0-9][0-9][0-9][0-9][0-9][0-9][0-9]$

Sample code:

using System.Text.RegularExpressions;
 Regex RegexObj = new Regex(@"^1\d{7}$");
 bool  result=   RegexObj.IsMatch("" );

–result has false value

If you don’t want to allow empty string then put following attribuite on the field.

[Required(AllowEmptyStrings = false)]