Selection

An effective computer program is one that can adapt or react to information that it is given. The ability for a program to decide what action to take based on a certain condition opens up huge potential for the usefulness of algorithms.

Selection

In programming, the term selection means that the program can choose to run different commands based on a condition being true or false.  For example if a user enters their age into a drivers license system and their age is less than 17, the program will tell them that they are too young.  If the users age is 17 or older then the user can be prompted with further instructions to apply for a license.

​There are two ways to achieve selection these are IF statements and Select Case statements
IF Statement

    









					
										
					
						



	

    

        
Case Statement

    

    

        

    









					
									

		
	













	

    

        
    
            
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    IF Statements
    
            
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    SELECT CASE
    
            
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IF Statements



If statements are a very simple but effective concept...

IF something is true > Do something
Else
​Do something else
















IF - Syntax



The CAIE recommended syntax for IF statements is as follows:​




	

		
			

				
					
						



	

    

        
IF Statement

    

    

        

    









					
										
					
						



	

    

        
IF with ELSE IF Statement

    

    

        

    









					
									

		
	









        

        

            
Select Case Statements



Case statements are particularly useful when there are many possible conditions.  They allow for a more efficient (less lines of code) algorithm:

























CASE - Syntax



The CAIE recommended syntax for CASE statements is as follows:​




	

    

        
SELECT CASE Statement

    

    

        

    













        

    


















	
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