Pseudocode

How to Write Pseudocode

Pseudocode is an intermediary step between reading a problem statement and writing the code to solve the problem. It serves as a blueprint for your program in order to guide you through it, in much the same way that contractors start with a blueprint before building a house. Use it as a tool to begin thinking about your program, but keep in mind it might not be the final solution to the problem. Pseudocode is written in a natural language using some programming keywords. Consider this example:

INCREMENT the number of apples in the basket by one

Notice how the example fully describes, in natural language, what needs to be done in the program. When writing pseudocode, start at the beginning of what you need the program to do and then work through step by step until reaching the end of what is required by the program in the problem statement. This is putting the problem in sequence. For example, making a peanut butter sandwich could be written as follows:

OBTAIN a plate

OBTAIN two slices of bread

OBTAIN a jar of peanut butter

OBTAIN a knife

Place the slices of bread on the plate

Open the jar of peanut butter

Spread peanut butter on one bread slice with the knife

Place the empty slice of bread on top of the slice with peanut butter Serve

There are several common keywords that get capitalized because they refer to actions taken in the program. Those words include READ, WRITE, PRINT, DISPLAY, CALCULATE, SET, and INCREMENT. Choices and loops can be shown in pseudocode. When an item is nested inside another item, indent that line of pseudocode, just like coding. Below are three generic examples:

IF condition THEN

Include the first sequence

ELSE

Include the second sequence

ENDIF

WHILE condition

Include the sequence

ENDWHILE

FOR loop parameters

Include the sequence

ENDFOR

You can also use the keyword CALL to reference another algorithm written separately. Now look at a more complete example of both good and bad pseudocode to get a general feel of how to write it:

Bad Example—Vague and Incomplete function doProgrammingHomework():

Get things for homework

Write the code correctly

Finish the homework

Bad Example—Too Technical, Does Not Follow Natural Language Usage function doProgrammingHomework():

getComputer(); openLearningEnvironment();

for (var count = 0; count < problems.length(); count++)

solve(); while (!compile) debug(); submit()

shutDownComputer();

Good Example–Follows Steps One at a Time Through the End of the Algorithm function doProgrammingHomework():

GET a computer

OPEN the learning environment module

FOR each of the problems in the module Complete problem

WHILE the problem does not compile

Debug

ENDWHILE

Submit the assignment

ENDFOR

Shut down the computer

Remember not to make your pseudocode too technical. You are not trying to write the code itself, just a plan to be used as a stepping stone after the initial problem to get your creative juices flowing.