Making DecisionsOften you will want a program to make decisions and perform different actions depending on  particular conditions. To do this you can use If…else statements. For example, if a school year greater than 13 was entered, the program could return a statement like 'This year group is too high' otherwise (else) it could return 'this year group is in the required range'. The program can also be made to select from a range of alternatives depending on the value entered using CASE statements. Click the arrow to view some examples.

if(guess == random number)   print "Well done" else    print "No. Bad guess"

if(guess > random number)   print "Guess is too high" else    print "Guess is too low'

IF…Else Statements This is an example of a program where the computer has to decide if a number you enter is equal to, greater than or less than a random number it has had to selected. click RUN to start

Press after number entered

Create a random number

RUN

Ask for user guess - please enter a guess between 1 and 100

You selected option

A

Click the arrow to see the code for this quiz.

B

Using the CASE statement

C

E

Cities of the world quiz Tap or click on the picture of Rome

D

var pick = (A, B, C, D or E depending on the image selected);

{case A:            messageBox.innerHTML = 'Sorry. This is Venice.';            break; case B:            messageBox.innerHTML = 'Sorry. This is Florence.';            break; case C:             messageBox.innerHTML = 'Well done. You selected Rome.';             break; case D:             messageBox.innerHTML = 'Sorry. This is Istanbul.';             break; case E:             messageBox.innerHTML = 'Sorry. This is Barcelona.';             break; }

switch(pick)

Move your mouse over a statement to hear an explanation.