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## Java

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**Java**Planning our Programs Flowcharts Arithmetic Operators**Planning Programs**• It is very important to plan our programs before we start coding • There are two ways of planning a program; • Pseudo-code = makes use of English statements to plot the program • 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 Plan**• The following is the Pseudo-code Plan for the previous program; 1. Start 2. 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**Start**N1 = 50 N2 = 13 tot = N1 + N2 Display tot End Flowchart Plan • The following is the Flowchart Plan of the previous program;**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**Terminator**• The terminator is used to show • The start and • The end of a program START END**Process**• A process is any action to be done by the program • N1 = 50 • N2 = 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 Raining? YES NO**Input/Output**• The Input/ Output symbol is used • When the program requires and input • When the program results in an output In this case the output to be shown is the contents of tot • Display tot**Try it out …**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); } } • Create • The pseudo-codes plan • The flowchart plan for the following program;**Arithmetic Operators**• Arithmetic Operators are used to perform mathematical calculations • The basic arithmetic operators ; • + (addition) • - (subtraction) • / (division) • * (multiplication) • % (remainder) These are called binary operators because they need to use at least two variables**Unary Operators**• Then are also what we call unary operators • These only need one variable • ++ (increment by 1) • -- (decrement by 1) • variable += x (same as variable = variable+ x) • variable -= x (same as variable = variable- x) • variable *= x (same as variable = variable* x) • variable /= x (same as variable = variable/ x) • variable %= x (same as variable = variable% x)**Combining Operators**• We could create a formula by combining a number of operators • The order the operators are work out is the following; • Multiplication • Division • Remainder • Addition • Subtraction X = 10 + 4 * 3 / 2; 10 + 4 * 3 / 2 10 + 12 / 2 10 + 6 16**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 / 2 14 * 3 / 2 42 / 2 21 As we can see the result has changed!!