[R] Readline - wait for user input

[Forest Floor]

Hi,

I've seen various posts on this question, but still can't get the code 
right. 

If I run the following code one line at a time, it works fine.  If I run 
it together as a block, however, it doesn't wait for the input and gives 
an error.

There must be a way to have are pause/wait for an answer, but I can't 
seem to find it.  Thanks!  J

Code:

choosefunction <- function(){readline("1. linear, 2. linear with lag, 3. 
nonlinear ")}
ans <- as.integer(choosefunction())
if (ans==1){K2=x1}
if (ans==2){K2=x2 }
if (ans==3){K2=x3 }
ans

Error text:
 > ans <- as.integer(choosefunction())
1. linear, 2. linear with lag, 3. nonlinear if (ans==1) {K2=x1}]}
Warning message:
NAs introduced by coercion
 > if (ans==2){K2=x2) }
Error in if (ans == 2) { : missing value where TRUE/FALSE needed
 > if (ans==3){K2=x3}
Error in if (ans == 3) { : missing value where TRUE/FALSE needed
 > ans
[1] NA