Functions become more powerful when they can be customized each time you run them. Swift lets you send values to a function that can then be used inside the function to change the way it behaves. We’ve used this already – we’ve been sending strings and integers to the print()
function, like this:
print("Hello, world!")
Values sent into functions this way are called parameters.
To make your own functions accept parameters, give each parameter a name, then a colon, then tell Swift the type of data it must be. All this goes inside the parentheses after your function name.
For example, we can write a function to print the square of any number:
func square(number: Int) {
print(number * number)
}
That tells Swift we expect to receive an Int
, and it should be called number
. This name is used both inside the function when you want to refer to the parameter, but also when you run the function, like this:
square(number: 8)
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