R help - May 2008 - R and C - variable by reference

Hi all,

I would like to know if it is possible in R to give a the reference of a
variable in a function; in order to be able  to change the variable in the
function and to keep the change when the function ended.
In other words, is it possible to code this following C code in R:
void functionName(int &var){}

Thanks a lot,
Naira
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Naira wrote:
> Hi all,
>
> I would like to know if it is possible in R to give a the reference of a
> variable in a function; in order to be able  to change the variable in the
> function and to keep the change when the function ended.
> In other words, is it possible to code this following C code in R:
> void functionName(int &var){}
No, not directly.  There are tricks to achieve the same thing (e.g. put 
the variable in an environment and pass the environment instead), but
generally speaking you are better off using R as if it was a functional 
language, i.e. avoiding side effects in your functions.  Use

x <- modify(x)

rather than expecting modify() to make changes to the things passed to it.

Duncan Murdoch