检测到文本框有一个数字和一个大写字母

Question

Hi I need to use regular expressions in C# to validate a TextBox.

Regular expressions should validate that the textbox has one number and one uppercase letter

My code is:

<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" 
    ControlToValidate="TextBox1" ErrorMessage="RegularExpressionValidator" 
    ValidationExpression="[A-Z a-z 0-9]*[0-1]+[A-z]+"></asp:RegularExpressionValidator>

but it's not allowing

nameA123

Where is my error?

Answer 1

Use this regex:

^(?=.*[A-Z])(?=.*[0-9])[a-zA-Z0-9]+$

In the regex demo , you can add strings to see if they match.

Explanation

• The ^ anchor asserts that we are at the beginning of the string
• The lookahead (?=.*[AZ]) asserts that at it is possible to match some chars then an uppercase letter
• The lookahead (?=.*[0-9]) asserts that at it is possible to match some chars then a digit
• [a-zA-Z0-9]+ matches letters and digits
• The $ anchor asserts that we are at the end of the string

Reference

• Lookahead and Lookbehind Zero-Length Assertions
• Mastering Lookahead and Lookbehind

Answer 2

The below regex would validates for atleast one uppercase alpha and one number and it won't care about any character including special characters.

^(?=.*[A-Z])(?=.*[0-9]).*$

DEMO