IBM C and C++ Compilers conforms to IEEE format, in which a floating point number is represented in terms of sign (S), exponent (E), and fraction (F):
(-1)S x 2E x 1.F
| Type | long double | |||||||||||||||||||||
| Alignment | ||||||||||||||||||||||
| Bit Mapping |
In the internal representation, there is
1 bit for the sign (S), 15 bits for the exponent (E), and
64 bits for the fraction (F). The bits are mapped with
the fraction in bit 0 to bit 63, the exponent in bit 64
to bit 78, and the sign in bit 79: Read the lines vertically from top to bottom. For example, the second column of numbers shows that bit 78 is part of the exponent. |
|||||||||||||||||||||
| Storage Mapping |
In the following mapping,
high memory is to the right.
|
![]()
Mapping of Fundamental Data Types
Mapping of Compound
Data Types
Format of Four-Byte
Floating Point Data
Format of Eight-Byte
Floating Point Data