Pseudo Code Examples

Formal pseudo code is used to clearly pin down the work that needs to be done when programming. Although some use an informal "list of steps", it is often useful to use formal pseudo code for more complex algorithms, since it is "sort of code" without the riggers of formal programming languages.The following is not complete and is not meant to be complete. It is simply the forms of pseudo code that would be used in a introduction to programming. It contains the sequential structure, the decision structure and the iteration or loop structure.

To begin the program code

START program name

To end the program code

STOP

The capitalized START and STOP are pseudo code words. They are in all capitals to draw attention to them. In this example the pseudo code words are also bold to draw even more attention. In practice bold letters are not required but I like them :).

The sequential structure is simply the statement that is required to explain the step. For instance to express a formula code

GrossPay = TotalHours * HourlyRate

In the example above I chose to capitalize the first letter of each word and run the words together to form "data elements" that might have been used in an IPO.

To ask the user of the program to enter the TotalHours data element in the example above two pseudo code words are used. It is known as a prompt.

OUTPUT Please enter the total hours for this employee.
INPUT TotalHours 

Notice how the pseudo code words pop out? Also notice that the data element name is used in the INPUT statement. The OUTPUT tells the user what is to be input in the next line. Was it total hours or perhaps overtime hours. The user needs to know what the program needs for each input

When decisions are required the IF statement is used. The first one shown is known as a NULL if. In the NULL if there is no "false" path

 		IF TotalHours > 40 THEN
			OUTPUT "You have exceeded the regual time. You are not authorized to work overtime"
	 ENDIF

In this next example the if is more complex. It is known as an IFTHENELSE. It is used to create two paths for the program. One path is for the condition when it is true the other when it is not true (it is false)


IF TotalHours > 40 THEN
	OTHours = TotalHours - 40
	RegHours = 40
ELSE
	RegHours = TotalHours
	OTHours = 0 	
ENDIF
GrossPay = (RegHours * RegRate)+(OTHours * RegRate * 1.5)
DISPLAY "Total Gross Pay is ",GrossPay 

Many true and many false statements can be placed in each part of the IF statement. True statements, that is statements that need to be executed if the IF is true go between the THEN and the ELSE. Those that are executed when the IF is false are placed between the ELSE and the ENDIF. If your IF structure does not require an ELSE the ENDIF is still required after all true statements.

The third structure is the iteration or loop structure. Lets code a small multiplication table

OUTPUT "Enter a number for the Table -> "
INPUT TheNumber
tableSize = 10
tableCount = 1
DOWHILE tableCount < tableSize
  tableAnswer = TheNumber * tableCount
  OUTPUT TheNumber " times ", tableCount, " equals ", tableAnswer
ENDDO

The output from the previous code would look something like this:

Enter a number for the Table -> 2

2 times 1 equals 2
2 times 2 equals 4
2 times 3 equals 6
2 times 4 equals 8
2 times 5 equals 10
2 times 6 equals 12
2 times 7 equals 14
2 times 8 equals 16
2 times 9 equals 18

2 times 10 equals 20

In addition you can create modules. An example of using modules follows.

START (this is the main program)
main program code starts here

now you need to call a module to do some code
CALL MyModule(parm1, parm2)

parm1 one now has a value that was calculated in MyModule
STOP (end of the main program)    
 
   
MyModule (arg1, arg2)

put some code here
arg1 = some equation here to return a value to the main program

RETURN