name <- "Alex"
# An empty string would be FALSE here
name_exists <- nzchar(name)
# name_exists = TRUE
num <- 7
is_ten <- num == 10
# is_ten = FALSE
# Any nonzero number is TRUE, 0 is FALSE
from_number <- as.logical(42)
# from_number = TRUE
# An empty vector: test its length
numbers <- c()
has_items <- length(numbers) > 0
# has_items = FALSE
# T and F are ordinary variables: they can change
T <- 0
t_changed <- T
# t_changed = 0
rm(T)
t_back <- T
# t_back = TRUE
cat("name_exists =", name_exists, "\n")
cat("is_ten =", is_ten, "\n")
cat("from_number =", from_number, "\n")
cat("has_items =", has_items, "\n")
cat("t_changed =", t_changed, "\n")
cat("t_back =", t_back, "\n")