C#•7d ago

OOP - Properties and Fields

Hello guys, sorry to disturb you all, consider the following code:

C#
namespace Classes;

public class BankAccount
{
    public string Number { get; }
    public string Owner { get; set; }
    public decimal Balance { get; }

    public void MakeDeposit(decimal amount, DateTime date, string note)
    {
    }

    public void MakeWithdrawal(decimal amount, DateTime date, string note)
    {
    }
}

C#
namespace Classes;

public class BankAccount
{
    public string Number { get; }
    public string Owner { get; set; }
    public decimal Balance { get; }

    public void MakeDeposit(decimal amount, DateTime date, string note)
    {
    }

    public void MakeWithdrawal(decimal amount, DateTime date, string note)
    {
    }
}

Noticed that we didn't defined the fields but only the properties which is used to get and set the variable. I have some questions. We didn't declare any fields or constructors, are the fields created automatically behind the scenes? For the constructor, we will be using the default constructor if nothing is provided?

13 Replies

FakerOP•7d ago

If I wanted to use conditions in the properties, like Owner should only contain alphabets, how can I do so pls here we would need to explicitly define the field?

Sossenbinder•7d ago

For properties, backing fields will automatically be generated, yes

Sossenbinder•7d ago

See https://sharplab.io/#v2:EYLgtghglgdgNAExAagD4wmApgZwA4QDGWABAMIA2EOOuA3ALABQzAAgMwmsBMJAQhBgBrAIKFCAewCuMAC7MA3sxIqunVgEYADCQByUsMCwAnEgpIBzLLLokAvstUcu2kgHkA7jBNnL127Q29o4qzghYhFCQFPwQVDDEvlZBDixMqmpcACwkALIQQlgAIlh4EjhQsgAU4ZHRJJjScnAuAHRFELJYACpRpAidWC2aOjASXQCUIWbTqdPOrDn5hQDqlQAWCMYQHnE1EVFxDWBNssMa7YO92CQDXeej41hT6apKryqpdkA

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FakerOP•7d ago

yep I see, this is valid only if I don't modify them to add certain conditions ?

Sossenbinder•7d ago

If you don't specify a custom constructor an implicit default constructor will be provided Oh, yeah, if you want to modify the behaviour of the getter or setter you'll have to do some work yourself There's an ongoing proposal / implementation to add a field keyword But it's not quite there yet https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/properties#field-backed-properties

FakerOP•7d ago

thanks, will have a look !

Sossenbinder•7d ago

Yw! Regarding your other question, if you want to add conditions to the properties, you could e.g. modify the setter to check the assigned value

FakerOP•7d ago

yeah, I should follow the following syntax:

C#
public class Person
{
    public string? FirstName 
    { 
        get;
        set => field = value.Trim(); 
    }

    // Omitted for brevity.
}

C#
public class Person
{
    public string? FirstName 
    { 
        get;
        set => field = value.Trim(); 
    }

    // Omitted for brevity.
}

For the getter and setters ?

Sossenbinder•7d ago

I think for the time being you'd be better off with using explicitly declared fields like showcased in https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/using-properties

Using Properties - C#

These examples illustrate using properties in C#. See how the get and set accessors implement read and write access and find out about uses for properties.

Sossenbinder•7d ago

The field keyword requires you to turn on some language preview settings

FakerOP•7d ago

yep I see, will just create a class, add some stuff and came back

C#
public string Name()
    {
        get {
            return _name;
        }
        set
        {
            _name = value;
        }
    }

C#
public string Name()
    {
        get {
            return _name;
        }
        set
        {
            _name = value;
        }
    }

Can someone explain why is the code above wrong please, my IDE is telling me get, set and value can't be resolved

Sossenbinder•7d ago

The () parentheses are not valid syntax for properties Just remove them

FakerOP•7d ago

ahh yeah true sorry

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OOP - Properties and Fields

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