Decision making statements - T24

As a programmer, it is essential for you to make your program to work better in all the cases. So, based on the real-time data, you have to decide how the program should work. So, it is important to take decision.

Consider a simple case where you want to print the number provided by the user at runtime is even or odd. How to handle that in programs? Decision making statements comes in to play.

So, what is the syntax and how to use that?

IF condition THEN

                This block will execute when the if condition is satisfied or validated to true.

END

This is the syntax of the simple IF block.

Ok. If the condition is not satisfied, then what will happen. I need to do something when IF condition is failed. How to handle that? ELSE block should be introduced. Here is the syntax,

IF condition THEN

                This block will execute when the if condition is satisfied or validated to true.

END ELSE

                This block will execute when the if condition is validated to false.

END

Let’s code a simple program to find whether it is even or odd?

PROGRAM FIND.EVEN.OR.ODD

                CRT “Input a number”

                INPUT GET_NUMBER

                IF MOD(GET_NUMBER,2) EQ 0 THEN

                                CRT “The number is Even”

                END ELSE

                                CRT “The number is Odd”

                END

END

MOD () – function allows to find modulus of a number. i.e. it will find the remainder of a division.

This simple if statement catered the above scenario but if you have a tons of scenarios to be checked what should be done.

Are you planning to do, Nested IF..ELSE,

Of course you can do that,

IF condition THEN

                Statements

                You can use NESTED IF ELSE here too.

END ELSE

                IF condition THEN

                                Statements

                END ELSE

                                statements

                END

                Statements

END

But this is a bad idea. If you have 2 or 3 cases to be checked you can use this. When there are about ten cases, using IF ELSE will reduce the readability of the code and it may prone to errors. So, what is the alternative?

SWITCH statements

Let’s see how it becomes an alternative and readability

BEGIN CASE

                CASE condition

                                statements

                CASE condition 

                                Statements

                CASE 1

                                Statements

END CASE

How the case statement works?

If the condition in first case becomes true, the rest of the cases will not be executed. CASE 1 is the default case, it will be executed if all the CASE fails.

You have to place the case statements very carefully for the logic to work properly and as expected by you.

Let’s see an example for CASE statement for the clear understanding, below is the scenario.

Consider a 10 litre container that contains water, if the water is less than 2 litres, you should print warning message. If that is between 5 and 7, print “Sufficient amount of water is available”. If that goes above 9.5, print “Container almost full”.

Let’s code it,

PROGRAM Water_Indicator

                CRT “Enter the amount of water in container”

                INPUT Capacity

                BEGIN CASE

                                CASE Capacity LE 2

                                                CRT “Warning: Water content is low”

                                CASE Capacity GT 2 AND Capacity LT 7

                                                CRT “Sufficient amount of water is available”

                                CASE Capacity GT 9.5

                                                CRT “Container almost full”

                                CASE 1

                                                CRT “Error Unable to receive the water level”

                END CASE

END

Hope you understand the CASE statements. Each CASE will carefully depict the flow and so it improves readability. Still any queries, please feel free to let us know in the comments.