y<- character()
y2 <- ""
length(y)
length(y2)
class(y)
class(y2)

y1<- c("e", "12", "2")
y1

y3<- character(10)
y3[3]<-"third"
y3[12]<-"twelveth"
y3[11]<-"11"
y3
length(y3)

n=3
m="3"
is.character(m)
is.character(n)
as.character(n)

t<-c(1:5)
t
t2<-c(1:5,"a")
t2
t3<-c(1:4,TRUE,FALSE)
t3
class(t3)
class(t)
t4<-c(1:4, TRUE, FALSE, "a")
t4
df1<- data.frame(n=c(1:4,"a"), letters=c("a","b","23","1","4"))
df1
str(df1)