Data Flow

Test yourself

Passing Parameters

Passing parameters allows us to send data into a subroutine.

Passing parameters

Passing parameters is the process of passing a piece of data into a subroutine.
The data is then assigned into a local variable (parameter) inside of the subroutine.
We can then use this data inside the subroutine.

Parameters vs global variables

We could also pass data by putting it inside of a global variable.
This is considered bad practice, since it can be accessed by any subroutine. Passing parameters is a much more secure, and maintainable approach.

Returning Multiple Values

Sometimes a situation might arise where we wish to return multiple pieces of data from the same subroutine.

Returning values

Functions are subroutines that return a value.
Functions are limited to returning a single value, which is sometimes problematic.

Returning a list

One solution to this problem is to use a list of values.
We can create a list, and append each value we want to return.
This list can then be returned, containing all of the values.

Restructuring subroutines

In other scenarios, it can be a much better idea to restructure subroutines to return only a single value.
Often, multiple return values is a sign of poor program design.

1Introduction to Python

1.1Python

1.1.1Python

1.2Input & Output

1.2.1Input & Output

1.3Data Types

1.3.1Data Types

1.4Variables & Constants

1.4.1Variables & Constants

1.5Operators

1.5.1Arithmetic & Relational Operators

1.5.2Boolean & Assignment Operators 2

1.6Program Flow

1.6.1Selection

1.6.2Iteration

2Data Structures

2.1Lists & Strings

2.1.1Lists

2.1.2Strings

2.2File Handling

2.2.1File Handling

3Modularity

3.1Subroutines

3.1.1Subroutines

3.2Data Flow

3.2.1Data Flow

4Good Practice

4.1Naming & Whitespace

4.1.1Identifiers

4.1.2Whitespace

4.2Comments

4.2.1Comments

4.3Exceptions

4.3.1Exceptions

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