s<-0

for(i in 1:100){

s<-s+I(i%%2==0)*i

}

s

I() 

x <- 1
 while(x < 5) {x <- x+1; print(x);}
x 

print( )

#break

#next 

is.na(y)

y

na.rm=TRUE

NaN :═ Not a Number
NA: ═  Not Avilable(Missing)

all.equall()

all.equal()

if(all(1:10>0)) 

cat("All are positive")

if(any(1:10==5))

cat("There is a five")

1:10

"All are positive"

==5

 switch(2,"red","green","blue")
[1] "green"

> switch(1,"red","green","blue")
[1] "red" 

 x <- switch(4,"red","green","blue")
> x
NULL

> x <- switch(0,"red","green","blue")
> x
NULL

> switch("color", "color" = "red", "shape" = "square", "length" = 5)
[1] "red"

> switch("length", "color" = "red", "shape" = "square", "length" = 5)
[1] 5

x1 <- list(c(1, 2), c(3, 4))

x2 <- list(list(1, 2), list(3, 4))

x3 <- list(1, list(2, list(3)))