find-perimeter-pentagon()

Step 1: Understanding the Problem

The first step in solving any problem is to understand it. In this case, we want to create a function that will calculate and return the perimeter of a pentagon. The perimeter of a pentagon can be found using the formula: Perimeter = 5 * side where 'side' is the length of a side of the pentagon.

Here is the initial setup for our function:

func findPerimeterPentagon(side: Double) -> Double {
    // calculation will happen here
}

In Swift, functions are defined using the func keyword. Our function is taking one parameter 'side' of type Double and will return a value of type Double.

Step 2: Implementing the Formula inside the Function

Now, let's implement the formula for the perimeter of a pentagon inside our function:

func findPerimeterPentagon(side: Double) -> Double {
    let perimeter = 5 * side
    return perimeter
}

In this step, we declared a variable 'perimeter' and assigned it the calculated value of the pentagon's perimeter. The 'return' keyword is then used to specify the result of the function.

Step 3: Testing the Function

Once we have our function ready, we need to test it. Let's see it in action:

var result = findPerimeterPentagon(side: 10)
print(result) // expected output 50.0

This will calculate the perimeter of a pentagon of side 10, and the expected output should be 50.0

Step 4: Error Handling

Until now, our function is unable to handle any errors. For instance, the side-length cannot be negative. So, we add some error handling to account for that:

func findPerimeterPentagon(side: Double) -> Double {
    if (side < 0) { print("Error: side length can't be negative.")
    return 0
}
    let perimeter = 5 * side
    return perimeter
}

Here, we add an error checking statement. If the side is less than zero, the function will print an error message and return 0.

Step 5: Conclusion

Here is the final code:

func findPerimeterPentagon(side: Double) -> Double {
    if (side < 0) { print("Error: side length can't be negative.")
    return 0 }

    let perimeter = 5 * side
    return perimeter
}

We now have a swift function that takes a side length as an input, calculates the perimeter if the side length is positive, and handles the error when the side length is less than zero.