Passing first file in DIR command to a variable

Question

I want to pass the very first file returned by

dir *.png /B

into the variable %firstFile%

Answer 1

Why do you need dir?

for %%x in (*.png) do if not defined firstFile set "firstFile=%%x"

Answer 2

why do you need to iterate over all of the list?

for  %%x in (*.*) do (
  set "firstFile=%%x"
  goto :done
)
:done