2.4.5 Floating point literals

Floating point literals are described by the following lexical definitions:

floatnumber:    pointfloat | exponentfloat
pointfloat:     [intpart] fraction | intpart "."
exponentfloat:  (nonzerodigit digit* | pointfloat) exponent
intpart:        nonzerodigit digit* | "0"
fraction:       "." digit+
exponent:       ("e"|"E") ["+"|"-"] digit+

Note that the integer part of a floating point number cannot look like an octal integer. The allowed range of floating point literals is implementation-dependent. Some examples of floating point literals:

3.14    10.    .001    1e100    3.14e-10

Note that numeric literals do not include a sign; a phrase like -1 is actually an expression composed of the operator - and the literal 1.