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Passing references to parameters

A class is a reference type, and other data types such as Integer, float, Boolean, character, string, tuple, collection, enumeration, and struct are all value types.

Sometimes it is possible to pass a value type parameter as a reference, which is achievable, and theinout keyword provided by Swift can be implemented. Look at one of the following examples:

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2. Func Increment (inout value:double, amount:double = 1.0) {
6. Value + = Amount
10. }
18. var value: Double = 10.0
26. Increment (&value)
30. Print (value)
38. Increment (&value, amount:100.0)
42. Print (value)

Code Increment (&value) is the call function increment, the increment is the default value, where &value (add & symbol before the variable , take out the value address) is the way to pass the reference , when defining a function, the parameter identification corresponds to the inout.

Code Increment (&value,amount:100.0) is also called function increment, and the increase is 100.0.

The above code output results are as follows:

11.0

111.0

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