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C# Basics

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Method Arguments

4:30 with Jay McGavren

We can get our methods to accept arguments using method parameters.

  • It would be nice to be able to specify how long our Wait method should pause for.
  • We could do that by passing it an argument. For example, we could pass it the number of milliseconds to wait for: Wait(3000);
  • But if we try to run that code, we get an error: "No overload for method 'Wait' takes 1 arguments".
  • In other words, a call to Wait can't accept an argument... yet.
  • We can get it to accept one using method parameters.
  • Here's a program that declares an Add method that accepts two parameters, and a Subtract method that also accepts two parameters.
  • A parameter is a special variable that you declare at the start of a method.
    • It's just like declaring a variable; you specify a type and a name for the parameter.
    • You can specify multiple parameters by separating them with commas.
  • Within the method body, you can access the parameter just like you would a variable.
    • In the Add method, we print the value of the first parameter, and then print the value of the second parameter.
    • Then we print the result of adding first and second together.
  • When a method takes parameters, you need to provide argument values when calling that method.
    • C# sets each parameter variable with the value in the argument.
using System;

class Program
{
    static void Add(double first, double second)
    {
        Console.WriteLine(first);
        Console.WriteLine(second);
        Console.WriteLine(first + second);
    }

    static void Subtract(double first, double second)
    {
        Console.WriteLine(first);
        Console.WriteLine(second);
        Console.WriteLine(first - second);
    }

    static void Main(string[] args)
    {
        Add(3, 5); // => 8
        Add(10.5, 7.2); // => 17.7
        Subtract(9, 3); // => 6
        Subtract(21.3, 7.1); // => 14.2
    }
}
  • We can update Wait with a parameter, and pass arguments when we call it:
using System;
using System.Threading;

class Program
{

    static void Wait(int delay)
    {
        Console.WriteLine("Waiting...");
        Thread.Sleep(delay);
        Console.WriteLine("Done");
    }

    static void Main(string[] args)
    {
        Wait(1000);
        Wait(3000);
    }

}

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    We could do that by passing in an argument. 0:00
    For example, we can pass at the number of milliseconds to wait for. 0:00
    3,000 milliseconds will cause it to wait for 3 seconds. 0:05
    But if we save this code and try to run it, 0:09
    We get a compiler error, no overload for method Wait takes 1 arguments. 0:15
    In other words, a call to wait can accept an argument. 0:20
    We can give it to accept one using method parameters. 0:23
    Here's a program that declares an Add method that accepts two parameters and 0:27

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