• The IF statement.
• The SWITCH statement.

	Estimated duration: 20 mn

• IF... THEN... ELSE... END
• SWITCH...

Practical example

• We will test this statement with a simple WLanguage code example:
  1. If necessary, clear the "Initialization" event of the project and copy the following code.
     This code selects a number at random and displays a message according to the value.
     
     RandomNumber is int
     // Resets the random number generator
     InitRandom()
     // Selects a number at random between 100 and 4000
     RandomNumber = Random(100, 4000)
     Trace("Random number value " + RandomNumber)
     // Check if this number is strictly greater than 2000
     IF RandomNumber > 2000 THEN
     Trace("Number greater than 2000")
     ELSE
     Trace("Number less than or equal to 2000")
     END
     In this code, the expression to be evaluated is "RandomNumber>2000".
  2. Let's test this code: click in the quick access buttons.
  3. If necessary, open the "Debugger trace" pane to see the result: on the "Home" tab, in the "Environment" group, expand "Panes", select "Panes", and then select "Debugger trace".
  4. The "Debugger trace" pane will show the message that corresponds to your case (as the number is random, the message may change with each test!).

• In an IF statement, you can also cumulate conditions using the AND and OR keywords. Here are some simple examples you can test right away.
  • Compound condition with the AND keyword: Determines if two conditions are met. Both conditions are evaluated.
    
    // Compound condition (AND and OR keywords)
    Condition1 is boolean = False
    Condition2 is boolean = True
    // - AND keyword
    IF Condition1 AND Condition2 THEN
    Trace("Condition1 AND Condition2: <true>")
    ELSE
    Trace("Condition1 AND Condition2: <false>")
    END
    
    When you run the project test again, the "Debugger trace" pane will display:
    
    Condition1 AND Condition2: <false>
  • Compound condition with the OR keyword: Tests if either of the conditions are met. Again, both conditions are evaluated.
    
    Condition1 is boolean = False
    Condition2 is boolean = True
     
    IF Condition1 OR Condition2 THEN
    Trace("Condition1 OR Condition2: <true>")
    ELSE
    Trace("Condition1 OR Condition2: <false>")
    END
    
    When you run the project test again, the "Debugger trace" pane will display:
    
    Condition1 OR Condition2: <true>
    
    

    	Note	The second condition can be ignored if the first condition evaluates to false: simply use the _AND_ keyword. For example: Condition1 is boolean = False Condition2 is boolean = True   IF Condition1 _AND_ Condition2 THEN Trace("Condition1 _AND_ Condition2: <true>") ELSE Trace("Condition1 _AND_ Condition2: <false>") END When you run the project test again, the "Debugger trace" pane will display: Condition1 _AND_ Condition2: <false> Similarly, using the _OR_ keyword, if the first part of the expression is true, the rest of the expression is not evaluated.

• We will write some WLanguage code to try this statement:
  1. If necessary, clear the "Initialization" event of the project and copy the following code. This code retrieves the current date and displays a different message depending on its value. A specific message is displayed for the 1st and 15th of the month. In the other cases, the date of the corresponding day is displayed.
     
     // By default, the Date variable is initialized with the current date
     CurrentDate is Date
      
     // Checks the day of the date
     SWITCH CurrentDate.Day
     // 1st day of the month
     CASE 1: Trace("Today is the first day of the month.")
     // 15th day of the month
     CASE 15: Trace("Today is the 15th day of the month.")
     // For all other days, display the date
     OTHER CASE: Trace("Today is: " + CurrentDate.ToString())
     END
     
     

     	Note	Several functions and properties are available in WLanguage. Functions can take parameters and return results. Properties are directly applied to the controls or variables via the following syntax: <Name of control or variable>.<Property name> In our example, the Day property is used on the CurrentDate variable to get the day of the date.
  2. Let's test this code: click in the quick access buttons.
  3. The "Debugger trace" pane will show the message that corresponds to your case (the message may vary depending on the actual date!). For example, if the test is run on November 28, 2021, the following message will appear:
     
     Today is: 28/11/2021

• If the line "CASE 1:..." is executed, the other lines of code corresponding to the possible values are not executed.
• Several values can be grouped in the same case. The different values are separated by a comma. For example, to test the month of a date, we can write the following WLanguage code:
  
  SWITCH CurrentDate.Month
  // Months 1, 2 and 3
  CASE 1, 2, 3: Trace("We are in the first quarter of the year.")
  // Months 4 to 6
  CASE 4 <= * <= 6: Trace("We are in the second quarter of the year.")
  // Months after the sixth month
  CASE > 6: Trace ("We are in the second half of the year.")
  END
  
  For a project test run on November 28, 2021, the "Debugger trace" pane will display:
  
  Today is: 28/11/2021
  We are in the second half of the year.

• In our examples, the process corresponding to an expression value is written in a single line of code, directly after the "CASE X:" statement. You can also execute multiple lines of code. In this case, the lines of code are located under the "CASE X:" statement. The following syntax must be used:
  
  SWITCH <Expression>
  CASE Value 1:
  Process 1 - Line of code 1
  Process 1 - Line of code 2
  CASE Value N:
  Process N - Line of code 1
  Process N - Line of code 2
  OTHER CASE
  Process
  END