how to check Starting Digit of Text box greater than 6

Question

I have a problem for entering mobile no in text box that mobile no must start with 78 or 9 and Max size of textbox is 10.

Midhun T P · Answer

Hi Use regular expression for validation - function ValidateForm() { var mobile = document.getElementById(txtMobileNumber).value; var r = /^[789]\d{9}$/; if (!r.test(mobile)){ alert('Invalid mobile number'); return false; } }

Vandana Blogs · Answer

Thank You ! I Did it with : runat=server ControlToValidate=txtMobileNo ErrorMessage=Number Start with 78 or 9 ValidationExpression=^[789]\d{9}$ ValidationGroup=a>

Nitin Sontakke · Answer

Max size you can just manage with the MaxLength property so that is simple. To check if it begins with you have methods like BeginsWith. Or you have char array of the string so for example: if(txtMobileNumber.Text[0].IsNumber) if(txtMobileNumber.Text[0] == '7' || txtMobileNumber.Text[0] == '8' ||txtMobileNumber.Text[0] == '9') or something like that...hope that helps!