Real floating-point types

Generic, or binary, floating-point types consist of the following:

float
double
long double

IBM extension

Decimal floating-point types consist of the following:

_Decimal32
_Decimal64
_Decimal128

End of IBM extension

The magnitude ranges of the real floating-point types are given in the following table.

Table 10. Magnitude ranges of real floating-point types
Type	Range
float	approximately 1.2^-38 to 3.4³⁸
double, long double	approximately 2.2^-308 to 1.8³⁰⁸
_Decimal32	0.000001^-95 to 9.999999⁹⁶
_Decimal64	0.000000000000001^-383 to 9.999999999999999³⁸⁴
_Decimal128	0.000000000000000000000000000000001^-6143 to 9.999999999999999999999999999999999⁶¹⁴⁴

If a floating-point constant is too large or too small, the result is undefined by the language.

The declarator for a simple floating-point declaration is an identifier. Initialize a simple floating-point variable with a float constant or with a variable or expression that evaluates to an integer or floating-point number.

IBM extension

You can use decimal floating-point types with any of the operators that are supported for binary floating-point types. You can also perform implicit or explicit conversions between decimal floating-point types and all other integral types or generic floating-point types. However, these are the restrictions on the use of decimal floating-point types with other arithmetic types:

You cannot mix decimal floating-point types with generic floating-point types in arithmetic expressions, unless you use explicit conversions.
Implicit conversion between decimal floating-point types and real binary floating-point types is only allowed via assignment, with the simple assignment operator =. Implicit conversion is performed in simple assignments, which also include function argument assignments and function return values.

End of IBM extension

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