do-while loop in R

Pretty self explanatory.

repeat{  statements...  if(condition){    break  }}

Or something like that I would think. To get the effect of the do while loop, simply check for your condition at the end of the group of statements.

See ?Control or the R Language Definition:

> y=0> while(y <5){ print( y<-y+1) }[1] 1[1] 2[1] 3[1] 4[1] 5

So do_while does not exist as a separate construct in R, but you can fake it with:

repeat( { expressions}; if (! end_cond_expr ) {break} )

If you want to see the help page you cannot type ?while or ?repeat at the console but rather need to use ?'repeat' or ?'while'. All the "control-constructs" including if are on the same page and all need character quoting after the "?" so the interpreter doesn't see them as incomplete code and give you a continuation "+".

Building on the other answers, I wanted to share an example of using the while loop construct to achieve a do-while behaviour. By using a simple boolean variable in the while condition (initialized to TRUE), and then checking our actual condition later in the if statement. One could also use a break keyword instead of the continue <- FALSE inside the if statement (probably more efficient).

  df <- data.frame(X=c(), R=c())    x <- x0  continue <- TRUE  while(continue)  {    xi <- (11 * x) %% 16    df <- rbind(df, data.frame(X=x, R=xi))    x <- xi    if(xi == x0)    {      continue <- FALSE    }  }