• null expresses well the idea that the value is not here. It's not provided. Not available. It's neither a number, nor a zero/empty string or whatsoever. Don't use it for maximum or minimum values.

• int.MaxValue is strongly related to the language itself. Don't use int.MaxValue for a maximum speed limit of Vehicle class or a maximum acceptable speed for an aircraft, etc.

• Avoid magic values like -1 in your code. They are misleading and lead to mistakes in code.

• Create your own class which would be more straightforward, with the minimum/maximum values specified. For example VehicleSpeed can have VehicleSpeed.MaxValue.

• Don't follow any previous guideline and use magic values if it's a general convention for decades in a very specific field, used by most people writing code in this field.

• null expresses well the idea that the value is not here. It's not provided. Not available. It's neither a number, nor a zero/empty string or whatsoever. Don't use it for maximum or minimum values.

• int.MaxValue is strongly related to the language itself. Don't use int.MaxValue for a maximum speed limit of Vehicle class or a maximum acceptable speed for an aircraft, etc.

• Avoid magic values like -1 in your code. They are misleading and lead to mistakes in code.

• Create your own class which would be more straightforward, with the minimum/maximum values specified. For example VehicleSpeed can have VehicleSpeed.MaxValue.

• Don't follow any previous guideline and use magic values if it's a general convention for decades in a very specific field, used by most people writing code in this field.

• Don't forget to mix approaches. For example:

   class DnsQuery { public const int NoTimeout = 0; public int Timeout { get; set; } } this.query.Timeout = 0; // For people who are familiar with timeouts set to zero. // or this.query.Timeout = DnsQuery.NoTimeout; // For other people. 

Consider following points:

Using ∞ can be a solution for a maximum. JavaScript, for example, has an infinity. C# doesn't¹. There is int.MaxValue, but this is not your intent (int.MaxValue being the maximum integer, and not the maximum value accepted by your system), so you cannot use it.

For example, "Hello".IndexOf("Z") returns a magic value -1. It maybe makes it easier to manipulate the result:

but is not intuitive at all. Why -1 and not -123? A beginner may also mistakenly think that 0 means "Not found" too or just mistakenly type (position >= 0).

If your code is related to timeouts in network sockets, using something which was used by everyone for decades for the sake of being consistent is not a bad idea. Especially, 0 for a timeout is very clear: it's a value which cannot be zero. Using a custom class in this case may make things more difficult to understand:

• null express well the idea that the value is not here. It's not provided. Not available. It's neither a number, nor a zero/empty string or whatsoever. Don't use it for maximum or minimum values.

• int.MaxValue is strongly related to the language itself. Don't use int.MaxValue for a maximum speed limit of Vehicle class.

• Avoid magic values like -1 in your code. They are misleading and lead to mistakes in code.

• Create your own class which would be more straightforward, with the minimum/maximum values specified. For example VehicleSpeed can have VehicleSpeed.MaxValue.

• Use magic values if it's a general convention for decades in a very specific field, used by most people writing code in this field.

Consider:

Using ∞ can be a solution for a maximum.

• JavaScript, for example, has an infinity. C# doesn't¹.

• Ada, for example, has ranges. C# doesn't.

In C#, there is int.MaxValue, but you cannot use it in your case. int.MaxValue is the maximum integer, 2,147,483,647. If in your code, you have a maximum value of something, like a maximum accepted pressure before something explodes, using 2,147,483,647 has no sense.

For example, "Hello".IndexOf("Z") returns a magic value -1. It maybe makes it easier (does it?) to manipulate the result:

but is not intuitive at all. Why -1 and not -123? A beginner may also mistakenly think that 0 means "Not found" too or just mistype (position >= 0).

If your code is related to timeouts in network sockets, using something which was used by everyone for decades for the sake of being consistent is not a bad idea. Especially, 0 for a timeout is very clear: it's a value which cannot be zero. Using a custom class in this case may make things more difficult to understand:

• null expresses well the idea that the value is not here. It's not provided. Not available. It's neither a number, nor a zero/empty string or whatsoever. Don't use it for maximum or minimum values.

• int.MaxValue is strongly related to the language itself. Don't use int.MaxValue for a maximum speed limit of Vehicle class or a maximum acceptable speed for an aircraft, etc.

• Avoid magic values like -1 in your code. They are misleading and lead to mistakes in code.

• Create your own class which would be more straightforward, with the minimum/maximum values specified. For example VehicleSpeed can have VehicleSpeed.MaxValue.

• Don't follow any previous guideline and use magic values if it's a general convention for decades in a very specific field, used by most people writing code in this field.