Printting 'for' and 'while' indices

Sorry, I forgot to correct the message subject, so I am resending my
doubt it below:


 Hi all!

 I wrote a very basic program in R, which has some loops ('for' and
'while').  Is there a way to print the 'for' (or while) indice while the
program is running so that I am able to estimate where the program is
and how long it will last?

I mean, I want something like this:

i<-0
While(i<100){
"do a lot of commands"
"print i"
i<-i+1
}

How do I "print" the "i" at each step?

Thanks in advance,

Marcos