Variables & Constants (Cambridge (CIE) O Level Computer Science)

Variables & Constants

What is a variable?

• A variable is an identifier that can change in the lifetime of a program

• Identifiers should be:

  • In mixed case (Pascal case)

  • Only contain letters (A-Z, a-z)

  • Only contain digits (0-9)

  • Start with a capital letter and not a digit

• A variable can be associated a datatype when it is declared

• When a variable is declared, memory is allocated based on the data type indicated

What is a constant?

• A constant is an identifier set once in the lifetime of a program

• Constants are generally named in all uppercase characters

• Constants aid the readability and maintainability

• If a constant needs to be changed, it should only need to be altered in one place in the whole program