PSEUDOCODE C Programming Technique – Firdaus-Harun.com

Agenda Intro to Pseudocode Pseudocode vs Flowchart Technique – Write pseudocode Examples

What’s Pseudocode ? Artificial and Informal language Helps programmers to plan an algorithm Similar to everyday English Not an actual programming language

E.g : Pseudocode Read A, B Calculate C = A*B Display C Stop

Technique Do not write Start in every pseudocode Parallelogram – Read / Get OR Display / Print Rectangle – Specify the actions ◦ E.g:  Calculate A = B + C OR A equals to B plus C  Average = total / count  Final price equals price of item plus sales tax Diamond – [Next »]

Technique (..Cont.) Diamond ◦ Selection – IF, IF / ELSE and IF / ELSE IF IF A is less than B BIG = B SMALL = A ELSE BIG = A SMALL = B ◦ Repetition – WHILE / DO/WHILE / FOR [Next example]

Comparative Between Flowchart vs Pseudocode Flowchart ◦ A graphical way of writing pseudocode ◦ Rounded rectangle – terminal ◦ Parallelogram – input / output ◦ Rectangle – actions ◦ Diamonds – decision / conditional ◦ Circles – connector

E.g : Flowchart Start Terminal. Program start here Stop Terminal Program end here Input. Enter values for A and B ProcessOutput

Comparative Between Flowchart vs Pseudocode (..Cont.) Pseudocode ◦ No syntax rule – Independent from any programming language ◦ Write in an ordinary language ◦ Uses a structure resembling computer structure ◦ No connector between pages

E.g : Pseudocode Read A, B Calculate C = A*B Display C Stop

E.g : Pseudocode Read A, B – Input Calculate C = A*B - Action Display C - Output Stop - Terminal

Example 2 (Selection) Read A, B IF A is less than B BIG = B SMALL = A ELSE BIG = A SMALL = B Write / Display BIG, SMALL Stop

Example 2 (Selection) Read A, B - Input IF A is less than B - Selection BIG = B - Action SMALL = A - Action ELSE - Selection BIG = A - Action SMALL = B - Action Write / Display BIG, SMALL - Output Stop - Terminal

Example 3 (Repetition) Set count to zero Set total to zero Read number WHILE ( not end-of-data ) increment count by 1 total = total + number read number IF ( count > 0 ) then average = total / count Display average Stop

Advantages Converting a pseudocode to a programming language is much more easier than converting a flowchart. As compared to flowchart, it is easier to modify a pseudocode of a program logic when program modifications are necessary.

Limitations In the cases of pseudocode, a graphic representation of program logic is not available. There are no standard rules to follow for using a pseudocode. ◦ Different programmers use their own style of writing pseudocode; and hence, ◦ Communication problem occurs due to lack of standardization.

Class Tutorial *Using previous Flowchart tutorial. Write a pseudocode to calculate Area and Perimeter of a trapezoid. Write an algorithm to set a Median for given number : ………………………..

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Review - Pseudocode An artificial and informal language that helps programmers develop algorithms A "text-based" detail (algorithmic) design tool “Write the steps before you write the code” (Matthew Morgenstern –Computer Scientist)

Example – IF/ELSE Read student ‘s grade IF student's grade is greater than or equal to 60 Print "passed" ELSE Print "failed“ Stop

Example - WHILE Set total to zero Set grade counter to one WHILE grade counter is less than or equal to ten Input the next grade Add the grade into the total Set the class average to the total divided by ten Print the class average Stop

Example – WHILE & IF/ELSE Initialize total to zero Initialize counter to zero Input the first grade WHILE the user has not as yet entered the sentinel Add this grade into the running total Add one to the grade counter Input the next grade (possibly the sentinel) IF the counter is not equal to zero Set the average to the total divided by the counter Print the average ELSE Print “no grades were entered” Stop

EXAMPLE – WHILE & IF/ELSE Initialize passes to zero Initialize failures to zero Initialize student to one WHILE student counter is less than or equal to ten Input the next exam result IF the student passed Add one to passes ELSE Add one to failures Add one to student counter Print the number of passes Print the number of failures IF eight or more students passed Print "raise tuition“ Stop

Assignment 2: Pseudocode Please do this assignment as pair work. Your partner must be not same as previous assignment 1. Due date : 27 th July 2009 (in class)