What's the difference between `1L` and `1`?

Question

I often seen the symbol `1L` (or `2L`, `3L`, etc) appear in R code. Whats the difference between `1L` and `1`? `1==1L` evaluates to `TRUE`. Why is `1L` used in R code?

Answer 1

The "L" next to a whole number denotes an integer type.

For comparisons, run the following in R:

```

is.integer(1) # Outputs to FALSE. This is because it is a double type (run typeof(1)).

is.integer(1L) # Outputs to TRUE.

```

It looks off-putting, I agree: it is a strange way for R to differentiate between an integer "1" and a double "1" even though they're the same value!