PSEUDOCODE

It is a conventional code to represent an algorithm

PSEUDOCODE

It is a conventional code to represent an algorithm

PSEUDOCODE NOTATION

Refers the syntax used to write an algorithm in pseudocode

PSEUDOCODE NOTATION

Start an algorithm Algortihm NameOfTheAlgorithm {Finish an algorithm }

Data Types

Primitives DataInteger number intReal number (Floating point) doubleCharacter (single alphanumeric symbol) charBoolean data (FALSE/TRUE) boolean

Objects DataString (collection of chars) String

Data Types

Default valuesint 0double 0.0char ‘ ‘boolean FALSEString null

Char values should be shown between ‘ ‘String values should be shown between “ “

Variable

Is an abstract field which represent a storage location with a particular name.

Abstract Field

Physical storage location

Is a reference of

Variable

Different types of data could be stored in variables. Those data could change their value depending of different operations done with them

45 Data stored * 2 90

Naming a variable

• Is convenient to label the storage location with a name:• Variable names are letters (A..Z, a..z) combined with decimal digits (0..9) and the

underline symbol (_)• No length limits• No allowable special symbols (#$%&/()[]{}.,;!|…)• Variable names are case sensitive • “Variable names are all capitals, for example, CITY”• Self-documented names

Assigning values

To store a value in a variable, the assignment operation should be done:

“Values will be assigned using = “, for example:AGE=35FIRSTNAME_OF_CLIENT=“Fernando”STATUS=TRUEGENDER=‘F’AREAOFCIRCLE=56.2345

Assigning values

Naming a variable

AGE

Assigning a value 45

AGE

AGE = 45

Creating a variable

To create the abstract field and the storage location of a variable, a “declaration”sentence has to be executed. This operation should be done previously to startusing the variable

Declaration syntax:

Data type variable_name = value ;Type of the data

to be storedName of the

variable

Assignment operation

Value to be stored

Sentence separator

Output information

Operation that indicates data is output in an output device: printer, screen, …Output syntax:• output (“Prompt”); The label is shown in an output device• output (variable); The content of the variable is shown an output device• output (“Prompt” + variable); The label and the content of the variable is

shown in an output device output (“Label” + variable);+ in this context is called “concatenation” operator, and it

means link the label and the variable value

Example

Problem: Given the value of a temperature in Celsius degrees, calculate the equivalentFahrenheit degrees value

Algorithm TemperaturesConvertion {double CELSIUS=0.0;double FAHRENHEIT=0.0;CELSIUS=37;FAHENHEIT=(9/5)*CELSIUS+32;output (CELSIUS+” °C are equivalent to “+FAHRENHEIT+” °F”);}

Input Data

Operation that permits to capture data from an input device and stores it in a variable.There are different instructions to input data for every data type.Input syntax:• inputString(String prompt); to get a String value • inputInt(String prompt); to get an integer value• inputDouble(String prompt); to get a double value• inputChar(String prompt); to get a char value• inputBoolean(String prompt); to get a boolean value

Example

Problem: Given the value of a temperature in Celsius degrees, calculate the equivalentFahrenheit degrees value

Algorithm TemperaturesConvertion {double CELSIUS=0.0;double FAHRENHEIT=0.0;CELSIUS=inputDouble(“Type the temperature in Celsius degrees”);FAHENHEIT=(9/5)*CELSIUS+32;output (CELSIUS+” °C are equivalent to “+FAHRENHEIT+” °F”);}

Operators

Arithmetic Operators:Relational Operators: Logic operators:

+ - * / %> >= < <= == !=&& || !

Are symbols to establish an arithmetic, logic or relational operations between data

Arithmetic Operators

Operator Computes Syntax Category

+ the sum of its two operands a + b Additive

- subtracts the second operand from the first

a - b Additive

* the product of its operands a * b Multiplicative

/ divides its first operand by its second operand

a / b Multiplicative

% the remainder after dividing its first operand by its second a % b Multiplicative

Relational Operators

Operator Computes Syntax Category

> Greater than a > b Relational

>= Greater than or equals to a >= b Relational

< Less than a < b Relational

<= Less than or equals to a <= b Relational

== Equals to a == b Relational

!= Is not equal to a != b Relational

Logical Operators

Operator Computes Syntax Category

&& Are both values TRUE? P1 && P2 Logic

|| Is, at least, one value TRUE? P1 || P2 Logic

! Is the opposite logical value !P1 Logic

Operators Precedence Category Operator Asociativity

Postfix ( ) Left to Right

Unary ! Right to Left

Multiplicative * / % Left to Right

Additive + - Left to Right

Relational < <= > >= Left to Right

Equality == != Left to Right

Logical AND && Left to Right

Logical OR || Left to Right

Assignment = Right to Left

Functions

Are pre-designed formulas to execute particular and complex calculations• sqrt(value) calculates the square root of a value• pow(base,power) calculates the result of an exponential expression 𝑥𝑥𝑦𝑦• abs(value) calculates the absolute value of a quantity • :• :

Exercise

In an University, the final grade of a subject is calculated by the weighted average ofthree grades. The weights of the grades are given as percentages respectively: 20% tothe first grade, 25% to the second grade and 55% to the third one, respectively. Developan algorithm, in pseudocode, which takes the personal information of any student andcalculate the final grade of a subject.

Exercise

La instalación de criaderos de peces, en una zona rural del Valle del Cauca, exige lacompilación de ciertos datos relacionados con los pescados que allí van a sembrarse: laespecie, la talla (el largo del pez) y el peso, serán características que en cada criaderose determinarán mediante sensores especiales de tecnología de control. Implementar unalgoritmo registre y calcule los datos necesarios para dar una información eficaz decualquier pez.

El factor de densidad lineal es un valor que permite generalizar y calcular el peso, dadosolamente el tamaño y que en este caso será 1.75.

CONTROL FLOW STATEMENTS

“Break up the flow of execution by employing decision making, looping, andbranching, enabling your program to conditionally execute particular blocks ofcode”

CONDITION

Is an expression which involves relational and/or logic operators. A boolean value is the result of a condition evaluation

Examples:AGE >=35AREA<23.7 AND SHAPE=“CIRCLE”

Tip: relational operators: > < >= <= ≠ ==Logic operators: AND OR NOT

if then STATEMENT

“It tells your algorithm to execute a certain section of code only if a particular test, of a condition, evaluates to true”

Syntaxif (condition) then

sentences for TRUE value;endif

if then STATEMENT

Example:A web site has implemented a routine that gives the access to its content only if the user type an appropriate password. Implement an algorithm to solve this situation

Algorithm AccessGranted{String PASSW=“AZ123b”, PASSUSER=null;PASSUSER=inputString(“Type the password”);if (PASSUSER=PASSW) thenoutput(“Welcome to the web site”);endif}

if then else STATEMENT

“The if-then-else statement provides a secondary path of execution when an "if" clause evaluates to false”

Syntaxif (condition) then

sentences for TRUE value;else

sentences for FALSE value;endif

if then STATEMENTExample:A web site has implemented a routine that gives the access to its content only if the user type anappropriate password; in other case a pop up window will notices the wrong password. Implement analgorithm to solve this situation

Algorithm AccessGranted{String PASSW=“AZ123b”, PASSUSER=null;PASSUSER=inputString(“Type the password”);if (PASSUSER=PASSW) thenoutput(“Welcome to the web site”);elseoutput(“Access hasn’t be granted !!!”);endif}

EXERCISESProblem 1:“Write an algorithm that recommends the number of calories a person should eat each day. Calories areunits of energy found in all foods. Base your recommendation on the person's weight and whether theperson has an active or sedentary (inactive) lifestyle. If the person is sedentary, that person's activityfactor is 13. If the person is active, that person's activity factor is 15. Multiply the activity factor by theperson's weight to get the recommended number of calories”

Problem 2:A code program to detect and advertise when a driver exceeds speed limits is required to be burned ina ROM memory and to be installed in a special device which will be used by the highway police.Develop a pseudocode of the algorithm to sketch the real program.

Problem 3:Given a natural number, determine if it is an odd or even number

Problem 4:Given two natural numbers A and B, determine if B is divisor of A

NESTED CONTROL FLOW STATEMENTSConsist of the combination or the link of two or more control flow statements to increase the functionalpower of an algorithm

NESTING IF THEN ELSE STATEMENTSSyntaxif (condition1) thensentences for TRUE value of condition 1;else if (condition2) thensentences for TRUE value of condition 2;else if (condition3) thensentences for TRUE value of condition 3;else if …..elsesentences for FALSE value all conditions;endif

if then STATEMENTExample:Classify a triangle given the three sides length

Algorithm Triangles {double SIDEA=0.0, SIDEB=0.0, SIDEC=0.0;SIDEA=inputDouble(“Length of side A”);SIDEB=inputDouble(“Length of side B”);SIDEC=inputDouble(“Length of side C”);if (SIDEA==SIDEB AND SIDEB==SIDEC) thenoutput (“Equilateral triangle”);else if (SIDEA==SIDEB OR SIDEA==SIDEC OR SIDEB==SIDEC) thenoutput (“Isosceles triangle”);else output (“Scalene triangle”);}

EXERCISES

Problem 1:Write a program to determine the cost of an automobile insurance premium, based on driver's age andthe number of accidents that the driver has had. The basic insurance charge is $500. There is asurcharge of $100 if the driver is under 25 and an additional surcharge for accidents:

# of accidents Accident Surcharge1 502 1253 2254 or more No insurance

EXERCISES

Problem 2:Windows performs a date format in two ways: a short format which shows the date as mm / dd / yyyy;and a long format mmmm-dd-yyyy

September-11-2013 (long format), 9/11/2013 (short format)

Implement an algorithm, in pseudocode, that permits to convert a format date from short to long format

EXERCISES

Problem 3:El personal que acude a un gimnasio deportivo se puede clasificar en “socios” o en“invitados”. El gimnasio cobra una tarifa fija por hora (no se cobran fracciones de la hora),pero para los socios hay un descuento del 20 % del valor a pagar . Además, para fomentar elejercicio físico en adultos mayores, el gimnasio ofrece un descuento adicional del 10% delvalor a pagar, a todas las personas con edad de 40 o más años. Desarrollar el algoritmo enpseudocódigo que permita calcular el valor a pagar por la utilización del gimnasio, de unapersona cualquiera

EXERCISES

Problem 4:• Given the Cartesian coordinates of a point P (x , y), calculate Polar coordinates of P (r , θ)• Given the polar coordinates of a point P (r , θ), calculate Cartesian coordinates of P (x , y)

Use the following information

FLOW CHART

It’s a graphic data representation of an algorithm.

Symbols:

Perform a Task

Manual Input

Start

EndDecision

Documentt

Display

Example Problem: Given the value of atemperature in Celsius degrees, calculatethe equivalent Fahrenheit degrees value

Algorithm TemperaturesConvertion {double CELSIUS=0.0;double FAHRENHEIT=0.0;CELSIUS=inputDouble(“Type the temperature in Celsius degrees”);FAHENHEIT=(9/5)*CELSIUS+32;output (CELSIUS+” °C are equivalent to “+FAHRENHEIT+” °C”);}

Start

CELSIUS=0.0

FAHRENHEIT=0.0

CELSIUS=inputDouble(“Type the temperature in Celsius degrees”)

FAHENHEIT=(9/5)*CELSIUS+32

output (CELSIUS+” °C are equivalent to “+FAHRENHEIT+” °C”);

End

while loop STATEMENT

“The while statement continually executes a block of statements while a particular condition is true”

Syntaxloop while conditionstatements;end loop

Condition StatementsYES

NO

while loop STATEMENT

Example: Print the first 5 even numbers out

Algorithm Serie1 {int COUNTER=1;loop while COUNTER < 5output(COUNTER*2+”\n”);COUNTER=COUNTER+1;end loop}

while loop STATEMENT

Example: Print the first 5 even numbers out

Algorithm Serie1 {int COUNTER=1;loop while COUNTER < 5output(COUNTER*2+”\n”);COUNTER=COUNTER+1;end loop}

A loop counter is a variable that increments or decrements its value

with a fixed quantity

COUNTER variable is a “loop counter”

while loop STATEMENT

Example: Print the following series numbers: 300, 250, 200, 150, 100, 50, 0

Algorithm Serie2 {int COUNTER=300;loop while COUNTER > -1output(COUNTER+”\n”);COUNTER=COUNTER-50;end loop}

while loop STATEMENT

Example: Determine the final printing of the following algorithm

Algorithm Serie1 {int COUNTER=0, NUMBER=0, ACUM=0;loop while COUNTER < 4NUMBER=inputInt(“Type a natural number”);ACUM=ACUM+NUMBER;COUNTER=COUNTER+1;end loopoutput(“The result is “+ACUM);}

while loop STATEMENT

Example: Determine the final printing of the following algorithm

Algorithm Serie1 {int COUNTER=0, NUMBER=0, ACUM=0;loop while COUNTER < 4NUMBER=inputInt(“Type a natural number”);ACUM=ACUM+NUMBER;COUNTER=COUNTER+1;end loopoutput(“The result is “+ACUM);}

A loop accumulator is a variable that increments or decrements its

value with a variable quantity

ACUM variable is a “loop accumulator”

while loop STATEMENT

Loop counter and loop accumulator operators:

N++ is equivalent to N=N+1N-- is equivalent to N=N-1

N+=c is equivalent to N=N+cN-=c is equivalent to N=N-cN*=c is equivalent to N=N*cN/=c is equivalent to N=N/c

Loop counter

If c is a constant value N is a loop counter

If c is a variable value N is a loop

accumulator

while loop STATEMENT

TRACE TABLE is a table used to test an algorithm by tracing the values of its variables during the algorithm flow

Variable 1 Variable 2 Variable 3 output

value value value value

value value value value

value value value value

while loop STATEMENT

Example: Determine the final printing of the following algorithm

Algorithm Serie1 {int COUNTER=0, NUMBER=0, ACUM=0;loop while COUNTER < 4NUMBER=inputInt(“Type a natural number”);ACUM=ACUM+NUMBER;COUNTER=COUNTER+1;end loopoutput(“The result is “+ACUM);}

Trace TableCOUNTER NUMBER ACUM OUTPUT

0 0 0

1 5 5 Type a natural number 5

2 2 7 Type a natural number 2

3 6 13 Type a natural number 6

4 3 16 Type a natural number 3

The result is 16

while loop STATEMENT

Exercises: 1. Print a sequence of asterisk characters depending of a given value2. Read and print values entered by a user until a particular sentinel value is

encountered. Do not print the sentinel value. Assume the sentinel value is stored in a constant called SENTINEL.

3. Print the numbers between LOW and HIGH that are evenly divisible by four but not by five.

4. Given a natural number, determine if it is a “perfect number”5. Generate the “Fibonacci numbers”

from/to loop STATEMENT

Syntaxloop counter from counter initial value to counter final value statements;end loop

Condition (involving

the counter)

NO

YES

counter declaration

statements

counter increasing/decreasing

from/to loop STATEMENT

Example: Write and algorithm in pseudocode to calculate the average of the students ages in a certain classroom

Algorithm TheAverage {int QUANTITY=0, COUNTER=0, ACUM=0, AGE=0;QUANTITY=inputInt(“Type the quantity of students”);loop COUNTER from 1 to QUANTITYAGE=inputInt(“Type the age”);ACUM += AGE;end loopoutput (“The average is “+(ACUM/QUANTITY));}

from/to loop STATEMENT

Example: Given a quantity of natural numbers, compute the sum of the odd numbers between 1 and the final number

Algorithm SumOdd{int QUANTITY=20, COUNTER=0; acum=0;QUANTITY=inputInt(“Type the amount of numbers”);loop COUNTER from 1 to QUANTITYif(counter mod 2 ≠ 0) thenACUM += NUMBER;end ifend loopoutput (“The sum is “+ACUM);}

from/to loop STATEMENT

Exercises: 1. Given a positive integer number, calculate its factorial2. “Write a program called HarmonicSum to compute the sum of a harmonic series, as shown below,

where n=50. “

3. “Write a program called ComputePI to compute the value of π, using the following series expansion. You have to decide on the termination criterion used in the computation (such as the number of terms used or the magnitude of an additional term). Is this series suitable for computing π?”

loop STATEMENTS

4. Write an algorithm in pseudocode to find out if a number is prime5. Develop the trace table to the following algorithm:

Algorithm Special {int N=0,M=0;N=inputInt (“Type a positive integer number”);loop while N>0N/=10;M++;end loopoutput (“Value “+M);

}

Approved notation for developing pseudocodehttp://occ.ibo.org/ibis/documents/dp/gr5/computer_science/d_4_comsc_sup_1201_1b_e.pdf

International Baccalaureate Organization 2012 IB Java Examination Tool Subset (JETS)http://occ.ibo.org/ibis/documents/dp/gr5/computer_science/d_4_comsc_sup_1201_1a_e.pdf

http://docs.oracle.com/javase/tutorial/java/nutsandbolts/flow.htmlhttp://visualbasic-dotnet-hindi.blogspot.com/2013/01/control-flow-statements.html