C# ToString メソッドのoverrideについて使い方を解説して

 Here's a comprehensive explanation of overriding the ToString method in C#:

What is the ToString method?

• It's a method inherited from the base Object class in C#.
• Its purpose is to return a string representation of an object.
• By default, it returns the fully qualified type name of the object, which isn't always informative.

Why override ToString?

• To provide a more meaningful string representation of your custom classes.
• To control how objects are displayed in various contexts, such as:
  • Console output
  • Debugging tools
  • Logging
  • User interfaces

How to override ToString:

1. Use the override keyword:

   • Declare the ToString method in your class with the override keyword.
   • This signals to the compiler that you're intentionally replacing the inherited version.

2. Provide a custom implementation:

   • Define the logic within the method to construct the desired string representation.
   • Typically, you'll concatenate relevant properties or values of the object.

Example:

C#

class Person
{
    public string Name { get; set; }
    public int Age { get; set; }

    public override string ToString()
    {
        return $"Name: {Name}, Age: {Age}";
    }
}

Person person = new Person { Name = "Alice", Age = 30 };
Console.WriteLine(person); // Output: Name: Alice, Age: 30

Key points:

• Always use the override keyword to prevent accidental errors.
• Keep your ToString implementation concise and informative.
• Consider using string formatting techniques for clarity and flexibility.
• Override ToString in base classes to provide a consistent representation for derived classes.

Additional tips:

• Use string interpolation or string.Format for cleaner string construction.
• Consider culture-specific formatting for internationalization.
• Handle null values appropriately to avoid exceptions.
• Test your ToString implementation thoroughly to ensure it produces the expected output.