Parameters as abstractions in AP CSP Pseudocode

The examples below use AP CSP Pseudocode. For Java, see Parameters as abstractions.

Abstractions in computer science hide details to manage complexity.

Commonly used abstractions include:

• Variables
• Procedures (often called methods or functions)
• Parameters (see details below)s
• Lists

Many procedures can be written more generally by using one or more parameters.

The example below assumes an understanding of:

• Writing and calling Procedures with parameters in AP CSP Pseudocode
• Traversals in AP CSP Pseudocode

Example: Searching for a value in a list

With a key parameter

PROCEDURE search(list, key)
{
    FOR EACH element IN list
    {
        IF(element = key)
        {
            RETURN(true)
        }
    }

    RETURN(false)
}

The search procedure returns true if its parameter key is in its parameter list, false otherwise.

Without a key parameter

PROCEDURE searchForFive(list)
{
    FOR EACH element IN list
    {
        IF(element = 5)
        {
            RETURN(true)
        }
    }

    RETURN(false)
}

PROCEDURE searchForTen(list)
{
    FOR EACH element IN list
    {
        IF(element = 10)
        {
            RETURN(true)
        }
    }

    RETURN(false)
}

The searchForFive and searchForTen procedure implement the same algorithm as the search procedure, but without the parameter key.

Without the parameter key, searchForFive must compare each value in list to 5 and searchForTen must compare each value to 10. Searching for a different value, such as 15, would require writing another version.

The parameter manages complexity

Parameters are abstractions because they allow the code inside a method to be written more generally.

Related examples

• Sequential/linear search
• Binary search

Help & comments

Get help from AP CS Tutor Brandon Horn

Comment on Parameters as abstractions in AP CSP Pseudocode