C# 7 Non-trailing Named Arguments


What is Named Arguments?

An argument with an argument-name is referred to as a named argument, whereas an argument without an argument name is a positional argument. The named arguments free you from matching the order of parameters in the parameter lists of called methods.

  • The parameter for each argument can be specified by parameter name.
  • Before C# 7.2, when you call a method with named arguments or optional parameters, all the named arguments must be specified at the end of the method signature after all the required arguments.
  • It was not allowed to appear a positional argument after a named argument in an argument list.

Let's consider the following example in which the PrintEmployeeInfo() method is called using named and optional arguments.

private static void PrintEmployeeInfo(string name, int age, string address, bool isActive = default, bool isManager = default)
{
    Console.WriteLine("Name: {0}, Age: {1}, Address: {2}, Is Active: {3}, Is Manager: {4}", name, age, address, isActive, isManager);
}

public static void Example()
{
    PrintEmployeeInfo("Mark", 24, "22 Ashdown close");
    PrintEmployeeInfo("John", 31, "9 Ashdown close", true, false);
    PrintEmployeeInfo(name:"Stella", age:29, address:"32 burak town", isActive:true, isManager:true);
    PrintEmployeeInfo(age:27, address:"81 wall street", name: "Andy", isManager: true, isActive: true);
}

Before C# 7.2, it was not allowed to specify the named arguments before positional arguments.

PrintEmployeeInfo(name:"Stella", age:29, address:"32 burak town", true, true);

Now in C# 7.2, it is allowed to have named arguments after positional ones.