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befpc/bepascal/docs/NumericalTypes.txt
2003-11-14 03:11:54 +00:00

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The following table shows correspondences between C/C++ and Pascal numerical types.
References are:
- FPC Reference guide (v1.0.8).
- The C Library Reference Guide, by Eric Huss.
C/C++ <-> BeAPI <-> Pascal
==========================
unsigned char = unit8 = Byte;
char = int8 = Shortint;
unsigned int = unit16 = Word;
short int = int16 = Smallint;
int = = We use Integer most times for this, but could be Smallint
unsigned long = uint32 = Longword;
long = int32 = Longint;
float = = Single;
double = = Double;
long double = = Extended;
C/C++ Types
===========
Type Size Range
---------------------------------
unsigned char 8 bits 0 to 255
char 8 bits -128 to 127
unsigned int 16 bits 0 to 65,535
short int 16 bits -32,768 to 32,767
int 16 bits -32,768 to 32,767
unsigned long 32 bits 0 to 4,294,967,295
long 32 bits -2,147,483,648 to 2,147,483,647
float 32 bits 1.17549435 * (10^-38) to 3.40282347 * (10^+38)
double 64 bits 2.2250738585072014 * (10^-308) to 1.7976931348623157 * (10^+308)
long double 80 bits 3.4 * (10^-4932) to 1.1 * (10^4932)
FPC Pascal Types
================
Type Size Range
-----------------------------
Byte 8 bits 0..255
ShortInt 8 bits -128..127
Word 16 bits 0..65535
SmallInt 16 bits -32768..32767
LongWord 32 bits 0..4294967295
LongInt 32 bits -2147483648..2147483647
Integer 16/32/64 either smallint, longint or int64 | These two depends on the
Cardinal 16/32/64 either word, longword or qword | compiler mode and platform.
Real 16/32 (depends on the platform)
Single 32 bits 1.5E-45 .. 3.4E38
Double 64 bits 5.0E-324 .. 1.7E308
Extended 80 bits 1.9E-4951 .. 1.1E4932
Int64 64 -9223372036854775808 .. 9223372036854775807
QWord 64 0 .. 18446744073709551615
Comp 64 -2E64+1 .. 2E63-1