How to cast List<A> to List<B>

How do I cast List<SelectVacancyDetails_Result> to List< SelectVacancyDetails_ResultExtend> where class SelectVacancyDetails_ResultExtend is inherited from class SelectVacancyDetails_Result.

I tried below but no luck

   List<SelectVacancyDetails_ResultExtend> vacExtList = vacList.Cast<SelectVacancyDetails_ResultExtend>().ToList();

(Basically i want all list properties value to be copied over)

If all the elements are actually of type SelectVacancyDetails_Result (not SelectVacancyDetails_ResultExtend) then you can't just cast. The simplest approach would be to create a constructor in SelectVacancyDetails_ResultExtend which copied the properties - or just used composition instead of inheritance, potentially - and then you can use:

var vacExtList = vacList.Select(vac => new SelectVacancyDetails_ResultExtend(vac))
                        .ToList();

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