How to loop through an list(CDT) and print its indexes in a grid?...

Not sure what you mean by printing its indexes but for looping on any list the Looping Functions are the best way to go. Please take some time to review this section of the documentation along with the examples to determine how these functions can help you meet your requirement forum.appian.com/.../Looping_Functions

I am trying to display the index of the list in one of my columns in the grid. Which function can i make use there?

There are several examples in the documentation. Take a look at each of them to see which will help you with your requirement, there's no better way to come up with an idea than reviewing the documentation and testing.

There are other easier options when it comes to find indexes in lists such as where() and wherecontains() forum.appian.com/.../Array_Functions
forum.appian.com/.../Array_Functions

can you not simply use enumerate(cdt.length)? this will give you a sequence number. If you want an index that starts with 1, you can try adding 1 using apply(sum, enumerate(cdt.length),1) - However, make sure your CDT has a column to store this info.

1+enumerate(cdt.length) is perhaps a cheaper way of doing this

thanks guys