Variable

A variable is a named location that holds a value.

Related concepts:  NameValueAssignment

Closest Wikipedia entry:  Variable (computer science)

Misconceptions about Variable

35 documented Misconceptions

AssignmentCopiesObject — Java

Assignment copies the object

CallerFrameContainsCalleeFormal — Java

Stack frame of caller includes variables for callee's formal parameters

ControlledLocalAccess — Java

One can control access to local variables using access modifiers

ExpressionAssigns — Java

An expression that reads a variable also updates its value after the evaluation

ForEachIteratesOverIndices — Java

An enhanced for loop iterates over the indices of an array or a collection

ForEachVariableIsElement — Java

One can assign to the variable of an enhanced for statement to store a value in the corresponding array or collection element

ForVariableScopeBeyondLoop — Java

The scope of variables declared in a for loop header extends beyond the loop

LocalVariablesAutoInitialized — Java

Local variables are automatically initialized

LoopBodyScopeImpliesLoopLifetime — Java

Lifetime of variables declared in a loop body extends across all loop iterations

MultiReferenceVariable — Java

A reference variable can point to multiple objects

MultiValueVariable — Java

A variable can contain more than one value

MustInitializeFieldInConstructor — Java

Constructors must assign values to all fields

NoAtomicExpression — Java

Expressions must consist of more than one piece

NoCastIfSameSize — Java

If a variable is at least as big (bit-width) as a value, then no cast is needed to a assign the value to the variable

NoLocalVariables — Java

There are no local variables

ReferenceToVariable — Java

References can point to variables

ThisAsField — Java

this is a special field in the object

ThisAssignable — Java

One can assign to this

ThisExistsInStaticMethod — Java

this is a local variable, also in static methods

UndeclaredVariables — Java

Variables can be used even without being declared beforehand

UntypedVariables — Java

Variable declarations don't need a type

UseOfSelfTypeImpliesRecursiveType — Java

If a class has a method that has a local variable, parameter, or return value with the class as its type, the class is a recursive type

VariablesHoldExpressions — Java

= stores an expression in a variable

VariablesHoldObjects — Java

A variable of a reference type contains a whole object

AssignmentCopiesObject — JavaScript

Assignment copies the object

ConstDeclarationCanBeLeftUninitialized — JavaScript

Declarations of constants do not need to be immediately initialized

NoAtomicExpression — JavaScript

Expressions must consist of more than one piece

ThisAssignable — JavaScript

One can assign to this

AssignmentCopiesObject — Python

Assignment copies the object

NoAtomicExpression — Python

Expressions must consist of more than one piece

SelfAssignable — Python

Reassigning self changes the object on which a method is called

VariablesHoldExpressions — Python

= stores an expression: it stores a reference to the expression in a variable

VariablesHoldObjects — Python

A variable contains a whole object

ExpressionAssigns — Scratch

An expression that reads a variable also updates its value after the evaluation

ResetStateEachProgramExecution — Scratch

Running a Scratch program first resets the state of the world and then executes the program