What is the difference between string and character in R?

Question

I'm not pretty familiar with R, but anyhow I'm writing a R wrapper for a c library. I come across this problem. How do I decide if the input argument is a string? In details,should I write like this:

dyn.load("hello.so")
do_process <- function(str) {
        if(!is.character(str))
            stop("not a character or string");
    result <- .Call("hello", as.character(str))
    return result
}

or this:

dyn.load("hello.so")
do_process <- function(str) {
        if(!is.string(str))
            stop("not a character or string");
    result <- .Call("hello", as.string(str))
    return result
}

Thanks.

Answer 1

is.string is a function from the xtable package. In the details section of the help page it explicitly says "These functions are private functions used by print.xtable. They are not intended to be used elsewhere."

As such, I would avoid using those functions.

In R there is no string data type. Instead it is called character and you can use is.character to do the check you're describing.

Also, as I mentioned in my comment, avoid using important base functions as variable names. Specifically str is used to view the structure of an object.