Expressions

Expressions are the pieces of code that produce values. They are used in assignments, conditions, function arguments, and return statements.

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Supported Expression Forms

• Number literals
• String literals
• Boolean literals
• Identifiers
• New expressions
• Enum member access expressions
• System function references
• Parenthesized expressions
• Invocation
• Member access
• Index access
• Unary operators
• Binary operators

Primary Expressions

• 123
• "hello"
• True
• name
• New Player
• Graphics
• (x + 1)

Calls, Members, and Indexes

• Foo()
• DoSomething(1, 2)
• Graphics(800, 600)
• foo.bar
• foo\bar
• arr[0]
• matrix[i, j]
• Direction.North

Postfix operations can be chained, such as foo.bar[1].baz(2). Both . and \ are recognized for member access. . is the preferred modern style.

Enum members are accessed with EnumName.MemberName. The bare enum name (for example Direction) is a type name and cannot be used by itself as a value expression.

If you are learning arrays for the first time, read Arrays for a step-by-step explanation of declarations, indexes, and common mistakes.

New Expressions

New <TypeName> allocates a new object for a user-defined Type.

Type Player
    Field Name As String
    Field Score As Integer
End Type

Dim currentPlayer As Player
currentPlayer = New Player

Unary Operators

• +
• -
• Not

• +1
• -value
• Not False

Binary Operators

• Logical: Or, And
• Comparison: =, <>, <, <=, >, >=
• Arithmetic: +, -, *, /, Mod, ^

Comparisons for Beginners

A comparison checks whether one value matches or relates to another value. The result of a comparison is always True or False.

• = means equal to
• <> means not equal to
• < means less than
• <= means less than or equal to
• > means greater than
• >= means greater than or equal to

You can compare variables to variables, variables to constants, or more complex expressions.

score = 10
health <= 0
playerX > enemyX
lives <> maxLives
(coins + bonus) > targetScore

Logical Conditions for Beginners

Use logical operators when a condition depends on more than one test.

• And means both sides must be True
• Or means either side can be True
• Not flips True to False and False to True

score >= 100 And lives > 0
health <= 0 Or timeLeft = 0
Not finished
(x > 0 And y > 0) Or debugMode

When a condition starts to look complicated, add parentheses to make the grouping clear.

Operator Precedence

From lowest to highest:

• 1. Or
• 2. And
• 3. =, <>, <, <=, >, >=
• 4. +, -
• 5. *, /, Mod
• 6. ^
• 7. Unary +, unary -, Not

Parentheses let you force a different order when needed.

• (X + (7 * DoSomething() / MyVar))