理解 - “$ result = imap_fetch_overview（$ mbox，”1：{$ check-> Nmsgs}“，0）;”[关闭]

I am tring to learn about the imap function, and I am struggling to understand:

$result = imap_fetch_overview($mbox,"1:{$check->Nmsgs}",0);

In particular $mbox,"1:{$check->Nmsgs}",0

PHP manual says it uses the X:Y syntax.

But I just cant get my head around it.

Please can anyone assist.

This is explained in the docs, which you should definitely start reading now:

When a string is specified in double quotes or with heredoc, variables are parsed within it.

And follow this link: http://php.net/manual/en/language.types.string.php#language.types.string.parsing