Arithmetic Expressions

Arithmetic expressions gather the expressions used for any arithmetic computation: addition, multiplication, substraction, division, modulo, shift left and right, bitwise or, bitwise exclusive, bitwise and, bitwise complement. This Section introduced these operators with a special focus on the additive operator which is a multi-purpose operator.

Additive Expression

The additive operator (i.e. +) is used for arithmetic addition of integers, floating point numbers and characters, and is also used for string concatenation, list or array concatenation and set or bag union. Its functionality depends on the type of its operands: it is a polymorphic operator. Note that the choice of its functionality is done at evaluation time, not at compile time. That means that the functionality of an expression such as x + y is unknown until the evaluation time. Depending on the dynamic type of the operands x and y, it can be a simple arithmetic addition, a string or list or array concatenation, a set or bag union or it can raise an error.
When used as a arithmetic operator and when the two operands have not the same type, one of the operands can be automatically promote to the type of the second one. The promotion mechanism is the same as in the C or C++ languages: integer may be promoted to float, char may be promoted to float or integer.

General Information
Operator	+
Type	binary
Syntax	expr + expr
Commutative	yes
Operand Types	integer, float, char, string, list, bag, set, array
Result Type	see following table
Function	multi functions according to operands: arithmetic addition, string concatenation, list or array concatenation, set or bag union.

Possible Operand Combinations
first operand type	second operand type	result type
integer	integer	integer
integer	float	float
char	char	integer
char	integer	integer
char	float	float
float	float	float
string	string	string	string concatenation
list	list	list	list concatenation
array	array	array	array concatenation
set	set	set	set union
bag	bag	bag	bag union

Expression Examples
expression	result
1 + 2	3
1 + 2.	3.
2 + 2.3	4.3
'a' + 'b'	195
'a' + 1.2	98.200
"hello" + "world"	"helloworld"
list(1, 2, 3) + list(2, 3, 4)	list(1, 2, 3, 2, 3, 4)
set(1, 2, 3) + set(2, 3, 4)	set(1, 2, 3, 4)
1 + "hello"	raises an error
set(1, 2, 3) + list(2, 3, 4)	raises an error

Multiplicative, Division and Minus Expressions

Multiplicative, division and minus expression syntax, semantics, associativity and precedence are quite identical to the corresponding C and C++ expressions. When operands have different types, promotionnal mechanisms are the same as for the additive operator.

General Information
Operators	-
	*
	/
Type	binary
Syntaxes	expr - expr
	expr * expr
	expr / expr
Commutative	- : no
	* : yes
	/ : no
Operand Types	integer, float, char
Result Type	see following table
Functions	- : substract
	* : multiply
	/ : divide

Possible Operand Combinations
first operand type	second operand type	result type
integer	integer	integer
integer	float	float
integer	char	integer
char	char	integer
char	integer	integer
char	float	float
float	float	float
float	integer	float
float	char	float

Expression Examples
expression	result
1 - 2	-1
3 * 2.	6.
2 * 'a'	194
'a' * 'b'	9506
1 / 2	0
1 / 2.	.5000
1. / 2	.5000
1. / 2	.5000
"hello" * "world"	raises an error
1 - "hello"	raises an error

Shift, Mod, And, Or, XOr Expressions

Shift, modulo, and, or and xor expression syntax, semantics, associativity and precedence are quite identical to the corresponding C and C++ expressions. Operand types must be integer or char and the only possible type promotion is from char to integer.

General Information
Operators	«
	»
	%
	&
	|
	^
Type	binary
Syntaxes	expr « expr
	expr » expr
	expr % expr
	expr & expr
	expr | expr
	expr ^ expr
Commutative	« : no
	» : no
	% : no
	& : yes
	| : yes
	^ : yes
Operand Types	integer, char
Result Type	integer
Functions	« : left shift
	» : right shift
	% : modulo
	& : bitwise and
	| : bitwise or
	^ : bitwise exclusive or

Expression Examples
expression	result
1 « 4	16
100 » 2	25
100 % 13	9
0xf12 & 0xf	2
0xf12 | 0xf	3871
0xf12 ^ 0xf	3869
'b' % '9'	8
2 « 1.2	raises an error
2 % 3.4	raises an error
2.1 % 3	raises an error

Sign Expressions

Sign expressions are the expressions using the unary operators + or -. The expression syntax, semantics, associativity and precedence are quite identical to the corresponding C and C++ expressions. These unary operators accept only integer, char and float operands.

General Information
Operators	+
	-
Type	unary
Syntaxes	+ expr
	- expr
Operand Types	integer, char, float
Result Type	see following table
Functions	sign operator

Possible Operand Combinations
operand type	result type
integer	integer
float	float
char	integer

Expression Examples
expression	result
+12	12
-100	-100
-123.4	-123.4
+'a'	97
-'a'	-97
+"hello"	raises an error
-null"	raises an error

Complement Expressions

The complement operator performs a bitwise complement on its operand. The expression syntax, semantics, associativity and precedence are quite identical to the corresponding C and C++ expressions. This operator accepts only integer and char operands.

General Information
Operator	~
Type	unary
Syntax	~ expr
Operand Types	integer, char
Result Type	integer
Functions	bitwise complement

Expression Examples
expression	result
~112	-113
~0	-1
~'a'	-98
~2.3	raises an error
~"hello"	raises an error