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Constants And Internal Representation
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ANSI C acknowledges that the size and numeric range of the basic data types (and their various permutations) are implementation-specific and usually derive from the architecture of the host computer. For CodeGear C++, the target platform is the IBM PC family (and compatibles), so the architecture of the Intel 80x86 and the Pentium family of microprocessors governs the choices of internal representations for the various data types.

The following tables list the sizes and resulting ranges of the data types. Internal representation of numerical types shows how these types are represented internally.

32-bit data types, sizes, and ranges

Type | Size (bits) | Range | Sample applications
unsigned char | 8 | 0 <= X <= 255 | Small numbers and full PC character set
char | 8 | -128 <= X <= 127 | Very small numbers and ASCII characters
short int | 16 | -32,768 <= X <= 32,767 | Counting, small numbers, loop control
unsigned int | 32 | 0 <= X <= 4,294,967,295 | Large numbers and loops
int | 32 | -2,147,483,648 <= X <= 2,147,483,647 | Counting, small numbers, loop control
unsigned long | 32 | 0 <= X <= 4,294,967,295 | Astronomical distances
enum | 32 | -2,147,483,648 <= X <= 2,147,483,647 | Ordered sets of values
long | 32 | -2,147,483,648 <= X <= 2,147,483,647 | Large numbers, populations
float | 32 | 1.18 ( 10^-38 < |X| < 3.40 ( 10^38 | Scientific (7-digit) precision)
double | 64 | 2.23 ( 10^-308 < |X| < 1.79 ( 10^308 | Scientific (15-digit precision)
long double | 80 | 3.37 ( 10^-4932 < |X| < 1.18 ( 10^4932 | Financial (18-digit precision)

See Also

Constants

Integer Constants

Integer Constant Without L Or U

Floating Point Constants

Character Constants

The Three Char Types

Escape Sequences

Wide-character And Multi-character Constants

String Constants

Enumeration Constants

Internal Representation Of Numerical Types

Constant Expressions

__int8

The Three Char Types

Internal Representation Of Numerical Types

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