Functions In Swift3.0

Today we learn about functions used in swift. Functions are self-contained chunks of code that perform a specific task.Swift functions contain parameter type and its return types.

Function Definition

In Swift, a function is defined by the "func" keyword. When a function is newly defined, it may take one or several values as input 'parameters' to the function and it will process the functions in the main body and pass back the values to the functions as output 'return types'.

Syntax

func funcName (Parameters) -> returntype {
    //Statements
   return parameters

} 

1) Function without  parameter and without return type

func learnSwift(){

  print("Hello Swift")

}

Explation:

 This function having no arguments and return type. func is keyword used before a function name.

"learnSwift" is the function name.

How to call function in Swift: 

Now open your xcode and create a new playground file. After function declaration  now its time to call your function.

2) Function with parameter and having no return type:

3) Function with multiple parameters and  having no return type :

4) Function with paramter and  having  return type:

Here learnSwift function having  String return type. myCurrentVersion is returned as String datatype.

Default Parameter Values :

Here "version" parameter is declared as default parameter value with "3.0"

Variadic Parameters

A variadic parameter accepts zero or more values of a specified type. You use a variadic parameter to specify that the parameter can be passed a varying number of input values when the function is called. Write variadic parameters by inserting three period characters (...) after the parameter’s type name.

The values passed to a variadic parameter are made available within the function’s body as an array of the appropriate type. For example, a variadic parameter with a name of numbers and a type of Double... is made available within the function’s body as a constant array called numbers of type [Double].

Note*

A function may have at most one variadic parameter.

In-Out Parameters :

Function parameters are constant by default. Trying to change the value of a function parameter from within the body of that function results in a compile-time error. This means that you can’t change the value of a parameter by mistake. If you want a function to modify a parameter’s value, and you want those changes to persist after the function call has ended, define that parameter as an in-out parameter instead.
You write an in-out parameter by placing the inout keyword right before a parameter’s type.

Note* In-out parameters cannot have default values, and variadic parameters cannot be marked as inout.

To modify the function parameters we can use  in-out parameter .

Conclusion:

All code in this post was tested against a playground in Xcode 8.

Today we learn about functions used in swift language.Since functions are so important to programming, they definitely need a lot of flexibility to do their job well.

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