PseudocodePseudocodeSkill Area 312 Part C
• Variable Types• Key Terms• Pseudocode• Pseudocode (Sequence)• Pseudocode (Selection)• Pseudocode (Iteration)• Examples
Reserved Words
• Words that has specific roles in the context in which it occurs, which cannot be used for other purposes.
Example:Example: IF – THEN – ELSEIF – THEN – ELSE DO – WHILE - DO – WHILE -
LOOPLOOP
Example:Example: PRINT, “”, :=PRINT, “”, :=
KeywordKeyword A A symbolsymbol in in
programming programming language that has a language that has a special meaningspecial meaning for for the compiler or the compiler or interpreter.interpreter.
• Pseudocode consists of short, English phrases used to explain specific tasks within a program’s algorithm.
• Used to provide an outline description of the specification for the software module
• Contain a natural language of expressions embedded in syntactic structures taken from programming language– IF…THEN…ELSE– REPEAT..UNTIL
• Not intended to be executed by a computer, must be interpreted by people.
PSEUDOCODEPSEUDOCODESEQUENCESEQUENCE
• When we write programs, we assume that the computer executes the program starting at the beginning and working its way to the end.
• This is a basic assumption of all algorithm design.
• We call this SEQUENCE.
• In pseudo-code it looks like this:
• For example, for making a cup of tea:
• Or as a program:
PSEUDOCODEPSEUDOCODESELECTIONSELECTION
• What if we want to make a choice– example, do we want to add sugar or not to
the tea?
• We call this SELECTION.
• So, we could state this as:
IF (sugar is required) THEN add sugar; ELSE don’t add sugar;ENDIF;
IF (sugar is required) THEN add sugar; ELSE don’t add sugar;ENDIF;
• Or, in general:
IF (<CONDITION>) THEN <Statements>; ELSE <Statements>;ENDIF;
IF (<CONDITION>) THEN <Statements>; ELSE <Statements>;ENDIF;
• Or to check which number is biggest:
IF (A > B) THEN Print A + “is bigger”; ELSE Print B + “is bigger”;ENDIF;
IF (A > B) THEN Print A + “is bigger”; ELSE Print B + “is bigger”;ENDIF;
• Adding a selection statement in the program:BEGIN
PROGRAM MakeACupOfTea: Organise everything together; Plug in kettle; Put teabag in cup; Put water into kettle; Wait for kettle to boil; Add water to cup; Remove teabag with spoon/fork; Add milk; IF (sugar is required) THEN add sugar; ELSE do nothing; ENDIF; Serve;END.
BEGINPROGRAM MakeACupOfTea: Organise everything together; Plug in kettle; Put teabag in cup; Put water into kettle; Wait for kettle to boil; Add water to cup; Remove teabag with spoon/fork; Add milk; IF (sugar is required) THEN add sugar; ELSE do nothing; ENDIF; Serve;END.
PSEUDOCODEPSEUDOCODEITERATIONITERATION
• What if we need to tell the computer to keep doing something until some condition occurs?
• Let’s say we wish to indicate that the you need to keep filling the kettle with water until it is full.
• We need a LOOP, or ITERATION.
WHILE Loop
REPEAT UNTIL Loop
FOR Loop
• So, we could state this as:
• Or to print out the numbers 1 to 5:
A = 1;WHILE(A > 5) DO Print A; A = A + 1;ENDWHILE;
A = 1;WHILE(A > 5) DO Print A; A = A + 1;ENDWHILE;
Get first entryIf this is the required entry
Then write down phone numberElse get next entryIf this is the correct entry
then write done entryelse get next entry
if this is the correct entry
Get first entryIf this is the required entry
Then write down phone numberElse get next entryIf this is the correct entry
then write done entryelse get next entry
if this is the correct entry
We may rewrite this as follows:
Get first entry;Call this entry N;WHILE N is NOT the required entryDO Get next entry;
Call this entry N;ENDWHILE;
Get first entry;Call this entry N;WHILE N is NOT the required entryDO Get next entry;
Call this entry N;ENDWHILE;
Consider the problem of searching for an entry in a phone book with only condition:
• Or as a program:
BEGINPROGRAM MakeACupOfTea: Organise everything together; Plug in kettle; Put teabag in cup; WHILE (Kettle is not full) DO keep filling kettle; ENDWHILE; Wait for kettle to boil; Add water to cup; Remove teabag with spoon/fork; Add milk; IF (sugar is required) THEN add sugar; ELSE do nothing; ENDIF; Serve;END
BEGINPROGRAM MakeACupOfTea: Organise everything together; Plug in kettle; Put teabag in cup; WHILE (Kettle is not full) DO keep filling kettle; ENDWHILE; Wait for kettle to boil; Add water to cup; Remove teabag with spoon/fork; Add milk; IF (sugar is required) THEN add sugar; ELSE do nothing; ENDIF; Serve;END
PSEUDOCODEPSEUDOCODEEXAMPLESEXAMPLES
• So let’s say we want to express the following algorithm:– Read in a number and print it out.
BEGINPROGRAM PrintNumber:Use variables: A OF TYPE Integer Read A; Print A;END
BEGINPROGRAM PrintNumber:Use variables: A OF TYPE Integer Read A; Print A;END
• So let’s say we want to express the following algorithm:– Read in a number and print it out double the number
BEGINPROGRAM PrintDoubleNumber:Use variables: A,B OF TYPE Integer Read A; B = A*2; Print B;END
BEGINPROGRAM PrintDoubleNumber:Use variables: A,B OF TYPE Integer Read A; B = A*2; Print B;END
• So let’s say we want to express the following algorithm to print out the bigger of two numbers:– Read in two numbers, call them A and B. Is A is bigger than B, print out A, otherwise print out
B.
BEGINPROGRAM PrintBiggerOfTwo:Use variables: A,B OF TYPE Integer Read A; Read B; IF (A>B) THEN Print A; ELSE Print B; ENDIF;END
BEGINPROGRAM PrintBiggerOfTwo:Use variables: A,B OF TYPE Integer Read A; Read B; IF (A>B) THEN Print A; ELSE Print B; ENDIF;END
• So let’s say we want to express the following algorithm to print out the bigger of three numbers:– Read in three numbers, call them A, B and C.
• If A is bigger than B, then if A is bigger than C, print out A, otherwise print out C. • If B is bigger than A, then if B is bigger than C, print out B, otherwise print out C.
BEGINPROGRAM BiggerOfThree:Use variables: A,B,C OF TYPE Integer Read A; Read B; Read C; IF (A>B) THEN IF (A>C) THEN Print A; ELSE Print C; END IF; ELSE IF (B>C) THEN Print B; ELSE Print C; END IF; END IF;END
BEGINPROGRAM BiggerOfThree:Use variables: A,B,C OF TYPE Integer Read A; Read B; Read C; IF (A>B) THEN IF (A>C) THEN Print A; ELSE Print C; END IF; ELSE IF (B>C) THEN Print B; ELSE Print C; END IF; END IF;END
• So let’s say we want to express the following algorithm:– Print out the numbers from 1 to 5
BEGINPROGRAM Print1to5:Use variables: A OF TYPE Integer A = 1; WHILE (A != 6) DO Print A; A = A + 1; ENDWHILE;END
BEGINPROGRAM Print1to5:Use variables: A OF TYPE Integer A = 1; WHILE (A != 6) DO Print A; A = A + 1; ENDWHILE;END
BEGINPROGRAM ComputeSum:Use variables: number1, number2, sum
OF TYPE IntegerDISPLAY “Enter the numbers”ACCEPT number1, number2Sum:=number1 + number2DISPLAY “SUM”END
BEGINPROGRAM ComputeSum:Use variables: number1, number2, sum
OF TYPE IntegerDISPLAY “Enter the numbers”ACCEPT number1, number2Sum:=number1 + number2DISPLAY “SUM”END
BEGINPROGRAM CategoryOfInsurance:Use variables: category OF TYPE character
insurance OF TYPE stringACCEPT categoryDO CASE of category
CASE category = UDISPLAY Insurance := “not available”
CASE category = ADISPLAY Insurance := “double”
CASE category = BDISPLAY Insurance := “normal”
CASE category = MDISPLAY Insurance := “medically dependent”
OTHERWISE DISPLAY “entry is invalid”ENDCASEEND
BEGINPROGRAM CategoryOfInsurance:Use variables: category OF TYPE character
insurance OF TYPE stringACCEPT categoryDO CASE of category
CASE category = UDISPLAY Insurance := “not available”
CASE category = ADISPLAY Insurance := “double”
CASE category = BDISPLAY Insurance := “normal”
CASE category = MDISPLAY Insurance := “medically dependent”
OTHERWISE DISPLAY “entry is invalid”ENDCASEEND
BEGINPROGRAM NumberRange0-100:Use variables: number
OF TYPE IntegerREPEAT
DISPLAY “Enter a numberbetween 0and 100”
ACCEPT numberUNTIL number <0 or number >100END
BEGINPROGRAM NumberRange0-100:Use variables: number
OF TYPE IntegerREPEAT
DISPLAY “Enter a numberbetween 0and 100”
ACCEPT numberUNTIL number <0 or number >100END
Create a flowchart for inputting your employee’s name. If the first letter starts from A to J then display “ First Category” , if K to T then display “ Second Category” otherwise display Third Category
Create a flowchart for inputting your employee’s name. If the first letter starts from A to J then display “ First Category” , if K to T then display “ Second Category” otherwise display Third Category
If student's grade is greater than or equal to 60Print "passed“ else Print "failed“If student's grade is greater than or equal to 60Print "passed“ else Print "failed“
Set the counter to 0. If the counter is more than 10 then customer receives free value meal otherwise no free value meal.
Set the counter to 0. If the counter is more than 10 then customer receives free value meal otherwise no free value meal.