Operators

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Free Pascal operators

Address operator

The address operator @ returns the start address of a variable, a procedure or a function. If the compiler switch is {$ T-}, the return value is an untyped pointer. If the compiler switch is {$ T +}, the return value is a typed pointer. The default setting for the compiler is {$ T-}.

Assignment operator

The assignment operator assigns a value to a data field.

  a := b;   // b is assigned to a

Relational operators

The following operations are possible:

• Integer and floating point data fields can be mixed on both sides of the operator.
• Short, ANSI and Widestring data fields can be mixed on both sides of the operator.

Operator	Meaning
=	equal
<>	not equal
<	less than
>	greater than
<=	less than or equal
>=	greater or equal
in	checks whether the element appears in a set of the same data type

Binary arithmetic operators

Operator	Meaning
+	addition
-	subtraction
*	multiplication
/	division
div	integer division (Calculates the integer value of how many times an integer is in another integer.)
mod	modulo division (Computes the integer remainder of a division of two integers.)

Unary arithmetic operators

+ specifies that the value is positive

- specifies that the value is negative

Examples:

   a := +7;
   b := -3;

Logical operators

Operator	Operation
not	Bitwise unary negation
and	Bitwise and
or	Bitwise or
xor	Bitwise exclusive or
shl	Bitwise shift to the left
shr	Bitwise shift to the right
<<	Bitwise shift to the left (corresponds with the operator shl)
>>	Bitwise shift to the right (corresponds with the operator shr)

Examples:

  A shr 1 // corresponds to integer DIV 2 (only that it is faster)
          // (only for integer data fields, the result is rounded down to an integer)
  Not 1   // corresponds to -2
  Not 0   // corresponds to -1
  Not -1  // corresponds to 0
  B shl 2 // corresponds to integer * 4 (only that it is faster)
          // (only for integer data fields, the result is an integer)
  1 or 2  // corresponds to 3
  3 xor 1 // corresponds to 2

Truth operators

Operator	Operation
not	logical negation (unary)
and	logical and
or	logical or
xor	logical xor

String operators

Operator	Operation
+	String concatenation (joins two strings together)

Set operators

Operator	Operation
+	union
-	difference set
*	intersection
><	symmetrical difference
<=	contains
include	add an item to the set
exclude	delete an item in the set
in	checks if the item is in the set

Class Operators

Operator	Operation
is	checks whether the object is of a certain class
as	performs a conditional type cast (conditional typecasting)

Pointer Operators

Operator	Operation	Operand type	Result type	Example
+	pointer addition	character pointer, integer	character pointer	P + I
-	pointer subtraction	character pointer, integer	character pointer	P - Q
^	pointer dereference	pointer	basic type of pointer	P^
=	equal	pointer	boolean	P = Q
<>	not equal	pointer	boolean	P <> Q

The priority of the operators

There is a rigid sequence for processing the operators.

Operators	Priority	Category
Not @	first (highest)	Unary operators
* / div mod and shl shr as << >>	second	Multiplication operators
+ - or xor	third	Addition operators
= <> < > <= >= in is	fourth (lowest)	Relational operators

See also

• Pascal basics