1. The Logic of the if-elseif-else Statement

The if-elseif-else statement is used when there are multiple conditions to check and only one of them can be true. The basic logic is:

   if condition1 is true
      do code block 1 and skip to whatever comes next (code block 5 below)
   else if condition2 is true
      do code block 2 and skip to whatever comes next (code block 5 below)
   else if condition3 is true
      do code block 3 and skip to whatever comes next (code block 5 below)
   else
      do code block 4
   end of the if-else if-else statement

   Do code block 5


In the if-elseif-else statement each condition is checked in order. As soon as a condition is found to be true, the code block for that branch is executed and then all the other conditions are skipped and the code continues with whatever comes next. If none of the conditions are true, the code in the else branch is executed before continuing with the program.

Note: The else branch is optional.

2. Using the if-elseif-else Block

We create an if-elseif-else block in a similar way as the if-else block. Click the gear icon on the if block and then drag the "else if" block under the "if" block and click them together:

The result is:

Then click the gear icon again to close the pop-up window. The final result is:

We can also drag multiple "else if" blocks during the dragging process and, if we want, drag over an "else" block at the end. A typical end result would look like this:

The examples show various ways if-elseif statements can be used.

3. Always Test All Possible Answers for if-elseif Statements

When you are using an if-elseif statement (or really, any kind of if statement), it's good to run the code with all possible variations of the condition that is being checked. You want to make sure it runs correctly in all cases. 

Note that

• If the else section is not there, then it's possible that the if-elseif statement won't do anything: when all the conditions are false, none of the if-elseif branches will be executed.


• If the condition or conditions to be checked are not mutually exclusive, then an if-elseif-else statement should not be used. Use individual if statements instead.