Scripting:Operators

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	| Function reference || AddressOf a		| Function reference || AddressOf a
	|-		|-
-	| Member b of a     || a.b	+	| Member (b of a)    || a.b
	|}		|}
		+
		+	== Precedence ==
		+
		+	The exact operator precedence is unknown. However, the following order of precedence seems to apply:
		+
		+	[*] Member, Function call
		+	[*] Increment, Decrement
		+	[*] Multiplication
		+	[*] Addition, Subtraction
		+	[*] Comparison
		+	[*] Logical NOT
		+	[*] Logical OR, Logical AND
		+	[*] Assignment
		+
		+	Operators with the same precedence seem to be applied from left to right. Keep in mind that the logical AND and OR are lazy. That is, if the left argument already dictates the outcome, the right argument is not evaluated. This is mainly important for arguments with side effects, such as function calls or the increment/decrement operators. It can also prevent referencing a NULL reference.
	== Notes ==		== Notes ==

---

Revision as of 12:34, 20 September 2010

Main | Syntax | Operators | Interfaces | FAQ | Contents | API Reference | Index

Contents 1 Table 1.1 String operators 1.2 Comparison operators 1.3 Arithmetic operators 1.4 Logical operators 1.5 Other operators 2 Precedence 3 Notes 3.1 Assignment operator v.s. equals operator 3.2 Increment and decrement operators 3.3 References equal 3.4 AddressOf

Table

In this section, a and b represent either literal values, object references or expressions evaluating to the appropriate type.

String operators

Operator name	Syntax
Concatenation	a & b

Comparison operators

Operator name	Syntax
Equals	a = b
References equal	a Is b
Not equal to	a <> b
Greater than	a > b
Less than	a < b
Greater than or equal to	a >= b
Less than or equal to	a <= b

Arithmetic operators

Operator name	Syntax
Assignment	a = b
Addition	a + b
Subtraction	a - b
Multiplication	a * b
Division	a / b
Increment	a++
Increment	++a
Decrement	a--
Decrement	--a

Logical operators

Operator name	Syntax
Logical NOT	NOT a
Logical AND	a AND b
Logical OR	a OR b

Other operators

Operator name	Syntax
Function call	a()
Function reference	AddressOf a
Member (b of a)	a.b

Precedence

The exact operator precedence is unknown. However, the following order of precedence seems to apply:

[*] Member, Function call [*] Increment, Decrement [*] Multiplication [*] Addition, Subtraction [*] Comparison [*] Logical NOT [*] Logical OR, Logical AND [*] Assignment

Operators with the same precedence seem to be applied from left to right. Keep in mind that the logical AND and OR are lazy. That is, if the left argument already dictates the outcome, the right argument is not evaluated. This is mainly important for arguments with side effects, such as function calls or the increment/decrement operators. It can also prevent referencing a NULL reference.

Notes

Assignment operator v.s. equals operator

The assignment operator and the equals operator use the same symbol. It depends on the context which operator is used. The assignment operator is used when a line of code follows the syntax Identifier = Value;. In all other cases, the equals operator is used.

Increment and decrement operators

There are two versions of the increment and decrement operators, namely the suffix and the prefix versions. The suffix versions increment or decrements the value hold by the identifier and then returns the old value. The prefix versions increment or decrement the value and return the result.

For example:

Var i As Integer = 5;
WriteLine(i++); // Writes 5
WriteLine(i);   // Writes 6
WriteLine(i--)  // Writes 6
WriteLine(i);   // Writes 5

i = 5;
WriteLine(++i); // Writes 6
WriteLine(i);   // Writes 6
WriteLine(--i); // Writes 5
WriteLine(i);   // Writes 5

References equal

The References equal operator returns true if both identifiers hold the same reference (or: point to the same object).

For example:

 Var i As String = "a";
 Var j As String = "a";
 WriteLine(i Is j); // false

 i = j;
 WriteLine(i Is j); // true

For types defined as Struct in the Object Explorer, this operator will never return true. When assigning one struct variable to another, the value is copied instead of the reference.

AddressOf

The AddressOf operator actually returns a CDelegate instance.

An example:

Var Delegate As CDelegate = AddressOf MyFunction;

Function MyFunction() {
  WriteLine("Hello universe!");
}

Delegate.Invoke();  // Writes "Hello universe!";