Switch...What does the switch statement do exactly when entered within a function

Question

Answer 1 · 2016-02-23T16:14:47Z

February 23, 2016 4:14pm

Hey Gregory, a switch statement allows certain blocks of code to be executed depending on the value of a control expression. Let me show you a simple example on how to use a switch statement within a function. For this particular example, I will make things easy. Let's say I have a function called calculator that takes 2 integers(a & b) and an enum of type Operation.

          <p>
enum Operation {

    case Addition, Subtraction, Multiplication, Division

}

func calculator(a: Int,b: Int, operation: Operation) -> String {

    }
 </p>
          ```

I want this function to return a string containing the result of any operation that I will pass into the function parameter and I want to add, multiply, divide and subtract. However, I don't want to write for every new operation a new function. Swift switch statement comes in handy because it allows us to kill two birds(even more than 2) with one stone. Instead of writing a new function that makes a subtraction for example, I can just switch on the enum value to let the function know what operation I want. Notice something, only the block of operation passed in to the operation parameter will be executed. Down below is how things will all look together:

```html
          <p>

// Here is the Operation Enum that will Allow me to switch on operations

enum Operation {

    case Addition, Subtraction, Multiplication, Division

}


func calculator(a: Int,b: Int, operation: Operation) -> String {

    // This variable returns the result of an operation

    var result: String = "No result"

    // Notice that after the switch word I used the parameter **operation** because I am switching on the different operations

    switch operation {

    // Within the switch statement, we can now write the logic for each of the operations

    case .Addition:

        result = "\(a) plus \(b) is equal to \(a + b)"

        return result

    case .Subtraction:

        result = "\(a) minus \(b) is equal to \(a - b)"

        return result

    case .Multiplication:

        result = "\(a) times \(b) is equal to \(a * b)"

        return result

    case .Division:

        result = "\(a) divided by \(b) is equal to \(a / b)"

        return result
    }

}

// Now if we call the function calculator  and input random numbers such as a = 12 and b = 6 and an operation of our choice, only the block of code corresponding to that operation will be executed and the console will print "12 divided by 6 is equal to 2".

 calculator(12, b: 6, operation: .Division)
</p>
          ```

I hope this example could help you better understand it.

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Gregory Millan

Gregory Millan

Switch...What does the switch statement do exactly when entered within a function

1 Answer

Frezy Mboumba

Frezy Mboumba