How should I write regex to validate below conditions:

• Total length of string should be between 4 to 6
• Last 3 characters should be digits only.
• String is only alphanumeric

eg: Valid strings: 1234, EC123, 1YC898, 001234

So far, I have tried below regex, but seems like I am missing something?

(^[a-zA-Z0-9]{4,6})?\d{3}$

How should I write regex to validate below conditions:

• Total length of string should be between 4 to 6
• Last 3 characters should be digits only.
• String is only alphanumeric

eg: Valid strings: 1234, EC123, 1YC898, 001234

So far, I have tried below regex, but seems like I am missing something?

(^[a-zA-Z0-9]{4,6})?\d{3}$

• javascript
• regex

Share Improve this question Follow asked Jul 21, 2014 at 17:35 johnk1johnk1 24788 silver badges1919 bronze badges 2

• debuggex. is great for trying your pattern and seeing why it works, or not, when you change it. The question is: what are you really trying to match. Is this homework with nonsense strings, or are you actually trying to find real strings from real data that need to match a specific pattern? – Mike 'Pomax' Kamermans Commented Jul 21, 2014 at 17:37
• Thanks for the link Mike. I am using regexr.. This is for one of my SAP UI5 application. Need to set a validation regex for one of the input field. – johnk1 Commented Jul 21, 2014 at 17:48

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1 Answer 1

Sorted by: Reset to default 5

You can use:

^[a-zA-Z0-9]{1,3}\d{3}$

• ^[a-zA-Z0-9]{1,3} will match 1 to 3 alpha-numerals at the start
• \d{3}$ will match 3 digits at the end of your input