Setting cookie using header("Set-cookie") vs setcookie() function

There's no good reason not to use setcookie. The above code doesn't properly encode names and values, so that's at least one major benefit to refactoring.

The difference between the two functions is that header() is the general function for setting HTTP headers while setcookie() is specifically meant to set the Set-Cookie header.

header() therefore takes a string containing the complete header, while setcookie() takes several cookie-specific arguments and then creates the Set-Cookie header from them.