Long double IEEE double extended floating point exponent of 15 bits and signed fraction of 64 bits.

Floating-Point literals may also be represented using exponential notation: a real number followed by the letter e(or E), followed by an optional plus or minus sign, followed by an integer exponent.

A floating literal consists of an integer part, a decimal point, a fraction part, ane or e, an optionally signed integer exponent, and an optional type suffix.