zip and download files using php

Question

I am trying to zip and download files from a folder named \"upload\". Zip file is downloading but I couldn\'t open (extract) it. I am getting an error like \"The archive is eith

Answer 1

Answer is good but Please add these lines before header. Zip file is open in all zip software (winzip, winrar etc.)

if (headers_sent()) 
    {
        // HTTP header has already been sent
        return false;
    }
// clean buffer(s)
while (ob_get_level() > 0)
    {
        ob_end_clean();
    }