Default Parameters

A parameter can have a default value when the caller leaves it out.

DefaultParameters.cs

using System;

class Program
{
    static string Label(string word, string suffix = "!")
    {
        return word + suffix;
    }

    static void Main()
    {
        string suffix = ;
        string defaultLabel = Label("ready");
        string customLabel = Label("ready", suffix);

        Console.WriteLine($"suffix={suffix}");
        Console.WriteLine($"default={defaultLabel}");
        Console.WriteLine($"custom={customLabel}");
    }
}

using System;

class Program
{
    static string Label(string word, string suffix = "!")
    {
        return word + suffix;
    }

    static void Main()
    {
        string suffix = ;
        string defaultLabel = Label("ready");
        string customLabel = Label("ready", suffix);

        Console.WriteLine($"suffix={suffix}");
        Console.WriteLine($"default={defaultLabel}");
        Console.WriteLine($"custom={customLabel}");
    }
}

using System;

class Program
{
    static string Label(string word, string suffix = "!")
    {
        return word + suffix;
    }

    static void Main()
    {
        string suffix = ;
        string defaultLabel = Label("ready");
        string customLabel = Label("ready", suffix);

        Console.WriteLine($"suffix={suffix}");
        Console.WriteLine($"default={defaultLabel}");
        Console.WriteLine($"custom={customLabel}");
    }
}

default parameter A default parameter supplies a fallback argument value.