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Lecture2Variablesand.PDF
Lecture 2: Variables and
Primitive Data Types
MIT-AITI Kenya 2005
1
In this lecture, you will learn…
• What a variable is
– Types of variables
– Naming of variables
– Variable assignment
• What a primitive data type is
• Other data types (ex. String)
MIT-Africa Internet
Technology Initiative
2 ©2005
What is a Variable?
• In basic algebra, variables are symbols
that can represent values in formulas.
• For example the variable x in the
formula f(x)=x2+2 can represent any
number value.
• Similarly, variables in computer program
are symbols for arbitrary data.
MIT-Africa Internet
Technology Initiative
3 ©2005
A Variable Analogy
• Think of variables as an empty box that
you can put values in.
• We can label the box with a name like
“Box X” and re-use it many times.
• Can perform tasks on the box without
caring about what’s inside:
– “Move Box X to Shelf A”
– “Put item Z in box”
– “Open Box X”
– “Remove contents from Box X”
MIT-Africa Internet
Technology Initiative
4 ©2005
Variables Types in Java
• Variables in Java have a type.
• The type defines what kinds of values a
variable is allowed to store.
• Think of a variable’s type as the size or
shape of the empty box.
2
• The variable x in f(x)=x
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