Are these Variables and Expressions notes free?

Yes. The full 4-page Variables and Expressions sheet is free inside CapCompass, which runs in your browser with no account needed.

What does the Variables and Expressions revision sheet cover?

Declaring and initialising a variable, Naming rules and conventions, Local scope against instance scope, the short version, Local variable, Instance variable, Operator families, Arithmetic, Relational, Logical, Assignment, Increment, decrement and the ternary operator, The array, one variable holding several values.

Is this for Class 11 ISC Computer Science?

Yes, it is written for the ISC Computer Science syllabus.

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Variables and Expressions — Class 11 ISC Computer Science revision notes

A 4-page visual revision sheet for Variables and Expressions, written for Class 11 ISC Computer Science. Formulas, diagrams and the traps that cost marks, laid out to be read the night before rather than the term before. Free, and it opens inside CapCompass.

Variables and Expressions revision notes, page 1 of 4 — A preview of page 1 — all 4 pages open full size in the app.

Variables and Expressions in one look

naming a value, then combining values into new ones

Declaring and initialising a variable

a declaration states a variable's type and name, such as int marks, and reserves it a slot of the right size
an initialisation gives that slot its first value, either on the same line as the declaration or on a later one
a local variable declared but never given a value cannot be used in an expression, the compiler rejects it as possibly unassigned, though a field of a class is given a default instead
several variables of the same type may be declared together on one line, their names separated by commas

Naming rules and conventions

a name must start with a letter, an underscore or a dollar sign, never a digit, and the rest may add digits too
Java is case sensitive, so total and Total name two different variables
a small fixed set of words is reserved by the language itself, such as class, if and int, and none of these may be used as a name
convention, not a rule the compiler enforces: variable and method names start lower case and grow a capital at each new word, such as totalMarks

Local scope against instance scope, the short version

Local variable

declared inside a method or a block
exists only while that method or block is running, then it is gone

Instance variable

declared inside a class, outside any method
exists for as long as the object holding it exists

Page 1 of 4. The full sheet, all 4 pages, opens free in the app.

What this Variables and Expressions sheet covers

Declaring and initialising a variable
Naming rules and conventions
Local scope against instance scope, the short version
Local variable
Instance variable
Operator families
Arithmetic
Relational
Logical
Assignment
Increment, decrement and the ternary operator
The array, one variable holding several values
Operator precedence, why order matters
Evaluating one mixed expression
Words the question will use
Traps that cost marks
Tricks that save time

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