Different ways to store data, defined by the set of values it can take and the set of operations which can be performed on it.

Data types made from existing data types, with a custom data structure.

Absolute control of the operations which can be performed on the data, so data cannot be accidentally, unusably changedMore memory efficient

A whole number value

-25, 0, 245

A number with a fractional part

-13.5, 0.2

A value which can only be TRUE or FALSE.

A letter, special character or number, represented in ASCII or Unicode.

"a", "4"

A collection of character values.

A ordered collection of fields, where each field may have a different data type.

A finite, indexed set of related elements which all have the same data type.

Giving a memory location an identifier or name.

Giving a memory location an with a value.

Variables are memory locations whose contents can change during the execution of a program, while constants are memory locations whose contents cannot change during execution of a program

1. No way that variable cannot accidentally be changed, as assignment can only occur once and its identifier is unique.
2. Quicker to change the value of a constant, as declaration can only occur at one location.
3. Makes code more readable, therefore quicker to debug.

Easier to readQuicker to understandEnables those unfamiliar with your code test, debug, and contribute (accessibility).

Repeating a set of instructions.

Repeating a set of instructions a known number of times.

Repeating a set of instructions an unknown number of times, until a Boolean condition is met.

The execution of statements in the order they appear (top to bottom).

Using relation operations to form Boolean conditions to decide if a set of instructions will be executed or not (IF statements).

Prevents the program from crashing due to an error and/or informs the user of a error in the program.

As an error occurs in a program, a exception is thrown. This computer handles the exception by pausing execution, saving the current state of the program to volatile store on the system stack and execution set of instruction defined within the catch block.

1. Opening files which may or may not exist.
2. Calling missing subroutines, variables etc..
3. Performing operation on data types which cannot occur (diving by 0, or index out of range).

1. Individual subroutines can be separately tested simultaneously, shortening development time.
2. Many subroutines can be written independently at the same time, shortening development time.
3. Subroutines reduces the repetition of code, less likely for typing errors.
4. Subroutines are compact and understandable as separate units, easier to read.
5. Subroutines are self contained, independent of global variables by way of parameters, so can be reused in other programs.

Both functions and procedures are types of subroutine, only functions return a value, while procedures do not return a value.

Variables which only exist while the subroutine is executing Which are only accessible within a subroutine.

Variables which can exist throughout the entire execution of a programWhich are accessible from any part of a program.

1. Local variables only exist on the call stack, so memory is freed up after a subroutine call and the program is memory efficient.
2. Local variables have reduced scope, so cannot be unknowing changed.
3. Local variables makes code modular.

A stack data structure where return return addresses, parameters and local variables (in that order) are pushed, containing all the data needed for a single subroutine call to be executed.

A system level stack data structure, containing many stack frames, used to control the order of subroutine execution and nesting.

1. The base case itself.
2. The base case must be met after a finite number of subroutine calls.
3. For all other input values other than the base case, the routine must call itself.

A Boolean condition, which when met will cause the routine to not call itself and unwind.