I want to connect my laptop with Arduino using RS232, is it necessary to use a voltage converter MAX232. or I can just use a voltage divider, or is there any other solution?
I believe you need a Max232 or equivalent.
The converter is necessary. Simple voltage divider is not usable. Years ago it used to be solved with discrete parts but now there is plenty ICs like MAX232, MAX3232 .... with 1..n inputs/outputs.