Maintaining Programs

Question 1

What is a variable?

Answer 1

A named space in memory that can be referred to by an single identifier and that can be changed during execution of a program.

Question 2

What is a constant?

Answer 2

A set value that can be referred to by a single identifier within the code, but cannot be changed.

This mean that the programmer only h as to change the value where the constant was declared, in order to alter it everywhere else in the code.

Question 3

What is an identifier?

Answer 3

A meaningful name, by which things like variables, constants and functions are referred to within code.

Question 4

What is a reserved word or keyword?

Answer 4

Reserved words or keywords are words that the programmer cannot use as identifiers because they are used by the actual programming language.

Question 5

What things improve the design/understanding of the code of a program?

Answer 5

Comments
Meaningful identifiers (variables, constants, functions)
Indentation
Line spacing
Top down/modular design/programming

Question 6

What is meant by the scope of a variable?

Answer 6

It refers to where in the code a variable that has been declared can be used.
A global variable is a variable declared in the main body of the source code, outside all functions, while a local variable is one declared within the body of a function or a block.

Question 7

What is meant by intialisation?

Answer 7

This is where starting values are set for variables before it is used in the program.

This is because a declared variable that hasn’t had a value put into it may have garbage data in it which can cause an error. Often, it is simply a case of putting zero or an empty string into the variable using normal assignment statements.