str_number <- "42"
number <- as.integer(str_number)
# Spaces around are ignored
padded <- as.integer(" 42 ")
# Not a number: NA, not 0
text <- "42 apples"
not_number <- suppressWarnings(as.integer(text))
cat("number =", number, "\n")
cat("padded =", padded, "\n")
cat("not_number =", not_number, "\n")
# The NA comes with a warning
msg <- tryCatch(as.integer(text),
warning = conditionMessage)
cat("msg =", msg, "\n")
# msg = NAs introduced by coercion