Assuming `qualified` is already declared, code a fall-through switch statement to print the following messages: When `qualified` is 1 or 2: "You are a student or teacher and you get a 10% discount." When `qualified` is 3 or 4: "You are a senior citizen or military and you get a 12% discount." For any other value of `qualified`: "Sorry, you're not eligible for a discount."

Here is how you can code a fall-through switch statement in a programming language like Java to achieve the described functionality. The concept of fall-through in switch statements is when a case doesn't have a `break` statement, it will "fall through" to the next case.

```java switch (qualified) { case 1: case 2: System.out.println("You are a student or teacher and you get a 10% discount.");

break;

case 3: case 4: System.out.println("You are a senior citizen or military and you get a 12% discount.");

break;

default: System.out.println("Sorry, you're not eligible for a discount."); } ```

In this block of code: - If `qualified` is 1 or 2, it prints "You are a student or teacher and you get a 10% discount." - If `qualified` is 3 or 4, it prints "You are a senior citizen or military and you get a 12% discount." - For any other value of `qualified`, it prints "Sorry, you're not eligible for a discount."

Extra: The switch statement in programming is used for decision making. Rather than using multiple `if ... else` statements, a switch allows you to choose one of many code blocks to execute. Here's how it generally works:

The switch expression is evaluated once. - The value of the expression is compared with the values of each case. - If there is a match, the associated block of code is executed. - The `break` statement is used to terminate a case in the switch statement. If it were not included at the end of a case, the switch statement would continue executing the following cases regardless of their values (fall-through). - The `default` case is optional and can be used for handling all other cases that are not explicitly handled by the other switch cases.

In programming languages like C, C++, and Java, the switch statement's fall-through behavior is sometimes utilized to allow multiple cases to execute the same piece of code, as shown in the example provided. In languages like JavaScript and PHP, the switch statement works similarly.

It's worth noting that some modern programming languages, like Swift, have designed their switch statements to be safer by avoiding fall-through by default. In these languages, including the explicit keyword `fallthrough` is necessary to achieve a traditional fall-through effect.