NumericConstants

R Base 3.6.2

How R parses numeric constants.

Details

R parses numeric constants in its input in a very similar way to C99 floating-point constants. Inf and NaN are numeric constants (with typeof(.) "double"). In text input (e.g., in scan and as.double), these are recognized ignoring case as is infinity as an alternative to Inf. NA_real_ and NA_integer_ are constants of types "double" and "integer" representing missing values. All other numeric constants start with a digit or period and are either a decimal or hexadecimal constant optionally followed by L. Hexadecimal constants start with 0x or 0X followed by a nonempty sequence from 0-9 a-f A-F . which is interpreted as a hexadecimal number, optionally followed by a binary exponent. A binary exponent consists of a P or p followed by an optional plus or minus sign followed by a non-empty sequ

Examples

Example

# NOT RUN {
## You can create numbers using fixed or scientific formatting.
2.1
2.1e10
-2.1E-10

## The resulting objects have class numeric and type double.
class(2.1)
typeof(2.1)

## This holds even if what you typed looked like an integer.
class(2)
typeof(2)

## If you actually wanted integers, use an "L" suffix.
class(2L)
typeof(2L)

## These are equal but not identical
2 == 2L
identical(2, 2L)

## You can write numbers between 0 and 1 without a leading "0"
## (but typically this makes code harder to read)
.1234

sqrt(1i) # remember elementary math?
utils::str(0xA0)
identical(1L, as.integer(1))

## You can combine the "0x" prefix with the "L" suffix :
identical(0xFL, as.integer(15))
# }

NumericConstants

Details

Examples

See Also