how do I validate form fields in sharepoint list?

Question

I want to validate the fields of the list item while adding/editing and stop the saving operation and provide the error information what the user made on that page itself.

Answer 1

You will likely have to start creating custom field controls to make this work. However, once you start down the path of customisation, you have a few options to think about.

You may like to think about either creating a custom asp.net form and coding it to post to the list or consider InfoPath forms.