> c<-c(1,2,3)
> mode(c)
[1] "numeric"
> c<-c(1,2,3,"r")
> mode(c)
[1] "character"
> d<-c(1,2,3)
> d[2]<-"test"
> d
[1] "1"    "test" "3"   
> mode(d)
[1] "character"