JavaPlanning our ProgramsFlowchartsArithmetic Operators

Planning Programs It is very important to plan our

programs before we start coding

There are two ways of planning a program;

1. Pseudo-code = makes use of English statements to plot the program

2. Flowcharts = use graphical symbols

Example Lets say we had the following

program class VariablesExample { public static void main (String args[]){ //variables are declared and assigned int N1 = 50; int N2 = 13; int tot; //the total of variables N1 and N2 //is stored in tot tot = N1 + N2; //Finally, we can show the result System.out.println(tot); }}

Pseudo-code PlanThe following is the Pseudo-code

Plan for the previous program;

1. Start2. Store 50 in N1.3. Store 13 in N2.4. Add N1 to N2 and store result in tot.5. Display the value in tot.6. Stop

Flowchart Plan The following is the Flowchart

Plan of the previous program;

Start

N1 = 50N2 = 13

tot = N1 + N2

Display tot

End

Why do we Plan Programs?We plan our programs in order to

know what we will be doing before we start coding

With a plan it will be much easier to know what structure our program will have

Planning makes programming much easier

Flowcharts A flowchart is basically a

graphical presentation of our program

A flowchart is very is to read and understand

Flowcharts break down our programs into many steps

Flowchart Symbols

Terminator The terminator is used to show1. The start and2. The end of a program

START

END

ProcessA process is any action to be

done by the program

N1 = 50N2 = 13

The process in this case is declaring two variables

Decision Decision are used when we have

a comparison Decisions have two outputs

which are YES or NO.

Is it Rainin

g?

YES

NO

Input/OutputThe Input/ Output symbol is used1. When the program requires and

input2. When the program results in an

output Display tot

In this case the output to be shown is the contents of tot

Try it out …Create1. The pseudo-codes plan 2. The flowchart plan for the following program;

class Variable{ public static void main (String args[]){ //variables are declared and assigned int N1 = 20; int N2 = 10; int tot; int tot2; //tot1 and tot 2 declared tot = N1 + N2; tot2 = N1 – N2; //Finally, we can show the result System.out.println(tot2); }}

Arithmetic OperatorsArithmetic Operators are used to

perform mathematical calculations

The basic arithmetic operators ;1. + (addition)2. - (subtraction)3. / (division)4. * (multiplication)5. % (remainder)

These are called binary operators because they need to use at least two variables

Unary OperatorsThen are also what we call unary operators

These only need one variable1. ++ (increment by 1)2. -- (decrement by 1)3. variable += x (same as variable = variable + x)

4. variable -= x (same as variable = variable - x)

5. variable *= x (same as variable = variable * x)

6. variable /= x (same as variable = variable / x)

7. variable %= x (same as variable = variable % x)

Combining OperatorsWe could create a formula by

combining a number of operators

The order the operators are work out is the following;

1. Multiplication2. Division3. Remainder4. Addition5. Subtraction

X = 10 + 4 * 3 / 2;

10 + 4 * 3 / 210 + 12 / 210 + 616

Use of Brackets When we use brackets in our

formula we are telling the program which operations to calculate first

X = (10 + 4) * 3 / 2;(10 + 4 ) * 3 / 214 * 3 / 242 / 221

As we can see the result has changed!!