Pascal for C users

Overview

This page gives some translations between C(++) and Pascal concepts.

Translation

Note: Logical operators (AND/OR/XOR etc) are logical or boolean depending on the type of the arguments (boolean or integer). Since Pascal had a separate boolean type from the start, boolean operators on integers were not necessary, and are always logical.

C	Pascal	Notes
{	Begin
}	End
=	:=	Becomes
==	=	Equal
/	/	Float Division (Integer: div)
%	Mod	Modulo operation
!	Not	Logical not
!=	<>	Not equal
&&	And	Logical and
<nowiki>		Or
&	And	Bitwise and
|	Or	Bitwise or
^	Xor	Exclusive or
~	Not	One's complement
>>	Shr	bit shift right   Note: shr is a logical bitshift, not arithmetic. If the left operand is a negative value of a signed type, then the result of an shr operation may not be what you expect.
<<	Shl	bit shift left
++	Inc
--	Dec
/*	{ or (*	Comment start
*/	} or *)	Comment end
//	//	End of line comment (only one line comment)
0x	$	prefix for hex-number e.g. $FFFFFF
0	&	prefix for oct-number e.g. &77777777
0b	%	prefix for bin-number e.g. %11111111
&	@	address operator
*	[[^]]	See Pointer and Pointers
if()	If Then
if() else	If Then Else
while	While Do
do while	Repeat Until Not
do while !	Repeat Until
for ++	For To Do
for --	For Downto Do
switch case break	Case Of End
switch case break default	Case Of Else End
const a_c_struct *arg	Constref arg : a_c_struct
a_c_struct *arg	Var arg : a_c_struct

C type	Pascal type	Size (bits)	Range	Notes
char	Char	8-bit		ASCII
signed char	Shortint	8-bit	-128 .. 127
unsigned char	Byte	8-bit	0 .. 255
char*	PChar	(32-bit)		Pointer to a null-terminated string
short int	Smallint	16-bit	-32768 .. 32767
unsigned short int	Word	16-bit	0 .. 65535
int	Integer	(16-bit or) 32-bit	-2147483648..2147483647	Generic integer types
unsigned int	Cardinal	(16-bit or) 32-bit	0 .. 4294967295	Generic integer types
long int	Longint	32-bit	-2147483648..2147483647
unsigned long int	Longword	32-bit	0 .. 4294967295
float	Single	32-bit	1.5E-45 .. 3.4E+38
double	Double	64-bit	5.0E-324 .. 1.7E+308
unsigned long long int	uInt64	64-bit	0 .. 18446744073709551616

C type	Pascal	Notes
struct { }	Record End
union { }	Record Case Of End	Variant Record

C	Pascal	Unit
abs	Abs	System
acos	ArcCos	Math
asin	ArcSin	Math
atan	ArcTan	System
atof	StrToFloat	SysUtils
atoi	StrToInt	SysUtils
atol	StrToInt	SysUtils
atoll	StrToInt64	SysUtils
ceil	Ceil	Math
cos	Cos	System
exp	Exp	System
floor	Floor	Math
pow	Power	Math
round	Round	System
sin	Sin	System
sqrt	Sqrt	System
strcpy	Copy	System
strlen	Length	System
tan	Tan	Math
toupper	UpCase	System

C++

C++ type	Pascal	Notes
class { }	Class End
class: { }	Class( ) End
template <class T> class { }	Generic = Class<T> End
struct { }	Object End	If you want methods

See also

• C to Pascal - conversion tools and libraries
• Short tutorial that describes the process of using C and C++ code in FreePascal, including writing of wrapper code
• Creating bindings for C libraries
• Common problems when converting C header files
• SWIG
• “Comparison of Pascal and C” on the English Wikipedia

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From the Free Pascal wiki, page "Pascal for C users", as it stood on 2022-12-03 after a change by Blueicaro, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's Licensing page. If you have concerns about this material, message the admin.