How will while loop work in sql server user defined function [duplicate]

Question

If I use a while loop inside my user defined function and the function returns a variable at last.. will the function return value for each iteration or will it return for only one iteration and end

If I consider a scenario as below

create or replace myFunction(
-- I declare some variables (input and locals)
@variable1 varchar(4000)
)
as
returns varchar(4000);

while loop begins

  do some calculations on variable1(for eg)

increment counter for while
end while loop

return @variable1;
end

In this case will return work for every while condition or only once.. What can be done to return for every while true condition

Thanks for the help!